Speed up CI

Author: aDotInTheVoid

.github/workflows/CI.yml

@@ -13,9 +13,7 @@ jobs:
   cargo-test:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2
-    - uses: actions-rs/toolchain@v1
-      with:
-        toolchain: nightly
-        profile: minimal
+    - uses: actions/checkout@v3
+    - uses: dtolnay/rust-toolchain@stable
+    - uses: Swatinem/rust-cache@v2
     - run: cargo test