Bump actions/checkout from 3 to 4 (rust-lang#2918)

Bumps [actions/checkout](https://github.com/actions/checkout) from 3 to
4.

Author: dependabot[bot]

.github/workflows/audit.yml

@@ -16,7 +16,7 @@ jobs:
   audit:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: EmbarkStudios/cargo-deny-action@v1
         with:
           arguments: --all-features --workspace

.github/workflows/bench.yml

@@ -30,14 +30,14 @@ jobs:
           echo "NEW_REF=${{ github.event.pull_request.head.sha }}" | tee -a "$GITHUB_ENV"
 
       - name: Check out Kani (old variant)
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           path: ./old
           ref: ${{ env.OLD_REF }}
           fetch-depth: 2
 
       - name: Check out Kani (new variant)
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           path: ./new
           ref: ${{ env.NEW_REF }}

.github/workflows/cbmc-latest.yml

@@ -22,7 +22,7 @@ jobs:
         os: [macos-12, ubuntu-20.04, ubuntu-22.04]
     steps:
       - name: Checkout Kani under "kani"
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           path: kani
 
@@ -37,7 +37,7 @@ jobs:
         run: cargo build-dev
 
       - name: Checkout CBMC under "cbmc"
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           repository: diffblue/cbmc
           path: cbmc
@@ -58,7 +58,7 @@ jobs:
     runs-on: ubuntu-20.04
     steps:
       - name: Checkout Kani under "kani"
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           path: kani
 
@@ -73,7 +73,7 @@ jobs:
         run: cargo build-dev -- --release
 
       - name: Checkout CBMC under "cbmc"
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           repository: diffblue/cbmc
           path: cbmc

.github/workflows/cbmc-update.yml

@@ -19,7 +19,7 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - name: Checkout Kani
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Setup Kani Dependencies
         uses: ./.github/actions/setup

.github/workflows/extra_jobs.yml

@@ -33,7 +33,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Checkout Kani
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
 
     - name: Label PR
       id: labeler

.github/workflows/format-check.yml

@@ -14,7 +14,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout Kani
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Execute copyright check
         run: ./scripts/ci/run-copyright-check.sh
@@ -33,7 +33,7 @@ jobs:
     runs-on: ubuntu-20.04
     steps:
       - name: Checkout Kani
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Setup Kani Dependencies
         uses: ./.github/actions/setup

.github/workflows/kani-m1.yml

@@ -16,7 +16,7 @@ jobs:
     runs-on: macos-13-xlarge
     steps:
       - name: Checkout Kani
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Setup Kani Dependencies
         uses: ./.github/actions/setup

.github/workflows/kani.yml

@@ -20,7 +20,7 @@ jobs:
         os: [macos-12, ubuntu-20.04, ubuntu-22.04]
     steps:
       - name: Checkout Kani
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Setup Kani Dependencies
         uses: ./.github/actions/setup
@@ -37,7 +37,7 @@ jobs:
     runs-on: ubuntu-20.04
     steps:
       - name: Checkout Kani
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Setup Kani Dependencies
         uses: ./.github/actions/setup
@@ -58,7 +58,7 @@ jobs:
     runs-on: ubuntu-20.04
     steps:
       - name: Checkout Kani
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Install benchcomp dependencies
         run: |
@@ -81,7 +81,7 @@ jobs:
     runs-on: ubuntu-20.04
     steps:
       - name: Checkout Kani
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Setup Kani Dependencies
         uses: ./.github/actions/setup
@@ -102,7 +102,7 @@ jobs:
       contents: write
     steps:
       - name: Checkout Kani
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Setup Kani Dependencies
         uses: ./.github/actions/setup

.github/workflows/release.yml

@@ -30,7 +30,7 @@ jobs:
       crate_version: ${{ steps.bundle.outputs.crate_version }}
     steps:
       - name: Checkout code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Setup Kani Dependencies
         uses: ./.github/actions/setup
@@ -135,7 +135,7 @@ jobs:
           cargo kani setup --use-local-bundle ./${{ matrix.prev_job.bundle }}
 
       - name: Checkout tests
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Run tests
         # TODO: Customize compiletest to run custom kani. For now, just run a few cargo kani tests.
@@ -160,7 +160,7 @@ jobs:
       KANI_SRC: ./kani_src
     steps:
       - name: Checkout Kani
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           path: ${{ env.KANI_SRC }}
 
@@ -204,7 +204,7 @@ jobs:
       upload_url: ${{ steps.create_release.outputs.upload_url }}
     steps:
       - name: Checkout code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Get version
         run: |
@@ -258,7 +258,7 @@ jobs:
       target: x86_64-unknown-linux-gnu
     steps:
       - name: Checkout code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Setup Kani Dependencies
         uses: ./.github/actions/setup

.github/workflows/slow-tests.yml

@@ -21,7 +21,7 @@ jobs:
         os: [macos-12, ubuntu-20.04, ubuntu-22.04]
     steps:
       - name: Checkout Kani
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Setup Kani Dependencies
         uses: ./.github/actions/setup

.github/workflows/toolchain-upgrade.yml

@@ -19,7 +19,7 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - name: Checkout Kani
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Setup Kani Dependencies
         uses: ./.github/actions/setup