fix(backport): Workaround not to fail if no backport is needed (#4707)

.github/workflows/backport.yml

@@ -11,16 +11,28 @@ jobs:
     if: github.event.pull_request.merged == true && !(contains(github.event.pull_request.labels.*.name, 'backport'))
     runs-on: ubuntu-latest
     steps:
+      # Workaround not to fail the workflow if the PR does not need a backport
+      # https://github.com/sorenlouv/backport-github-action/issues/127#issuecomment-2258561266
+      - name: Check for backport labels
+        id: check_labels
+        run: |-
+          labels='${{ toJSON(github.event.pull_request.labels.*.name) }}'
+          echo "$labels"
+          matched=$(echo "${labels}" | jq '. | map(select(startswith("backport-to-"))) | length')
+          echo "matched=$matched"
+          echo "matched=$matched" >> $GITHUB_OUTPUT
+
       - name: Backport Action
+        if: fromJSON(steps.check_labels.outputs.matched) > 0
         uses: sorenlouv/backport-github-action@v9.5.1
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}
           auto_backport_label_prefix: backport-to-
 
       - name: Info log
-        if: ${{ success() }}
+        if: ${{ success() && fromJSON(steps.check_labels.outputs.matched) > 0 }}
         run: cat ~/.backport/backport.info.log
 
       - name: Debug log
-        if: ${{ failure() }}
+        if: ${{ failure() && fromJSON(steps.check_labels.outputs.matched) > 0 }}
         run: cat ~/.backport/backport.debug.log