Fix regression re report-size-deltas after updating actions/upload-artifact.

For more information see https://github.com/arduino/report-size-deltas/blob/main/docs/FAQ.md#workflow-triggered-by-pull_request-event .

Author: aentinger

.github/workflows/compile-examples.yml

@@ -19,7 +19,7 @@ on:
   repository_dispatch:
 
 jobs:
-  build:
+  compile:
     name: ${{ matrix.board.fqbn }}
     runs-on: ubuntu-latest
 
@@ -95,9 +95,27 @@ jobs:
           enable-deltas-report: true
           sketches-report-path: ${{ env.SKETCHES_REPORTS_PATH }}
 
-      - name: Save sketches report as workflow artifact
+      - name: Upload sketches report to workflow artifact
         uses: actions/upload-artifact@v4
         with:
           if-no-files-found: error
           path: ${{ env.SKETCHES_REPORTS_PATH }}
           name: sketches-report-${{ matrix.board.artifact-name-suffix }}
+
+  # When using a matrix to compile for multiple boards, it's necessary to use a separate job for the deltas report
+  report:
+    needs: compile # Wait for the compile job to finish to get the data for the report
+    if: github.event_name == 'pull_request' # Only run the job when the workflow is triggered by a pull request
+    runs-on: ubuntu-latest
+
+    steps:
+      # This step is needed to get the size data produced by the compile jobs
+      - name: Download sketches reports artifacts
+        uses: actions/download-artifact@v4
+        with:
+          # All workflow artifacts will be downloaded to this location.
+          path: ${{ env.SKETCHES_REPORTS_PATH }}
+
+      - uses: arduino/report-size-deltas@v1
+        with:
+          sketches-reports-source: ${{ env.SKETCHES_REPORTS_PATH }}