ci: Make it possible to backport multiple commits (#3193)

.github/workflows/backport.yml

@@ -6,8 +6,24 @@ on:
       - 'main'
 
 jobs:
+  backport-commits:
+    runs-on: ubuntu-latest
+    outputs:
+      matrix: ${{ steps.commits.outputs.commits }}
+    steps:
+      - name: Get all commits in the push event
+        id: commits
+        run: |
+          commits_json=$(echo '${{ toJSON(github.event.commits) }}' | jq -c '[.[].id]')
+          echo "commits=${commits_json}" >> $GITHUB_OUTPUT
+
+
   backport-target-branch:
     runs-on: ubuntu-latest
+    needs: backport-commits
+    strategy:
+      matrix:
+        commits: ${{ fromJson(needs.backport-commits.outputs.matrix) }}
     outputs:
       matrix: ${{ steps.milestones.outputs.matrix }}
       latest_commit: ${{ steps.commit.outputs.latest_commit }}
@@ -22,6 +38,7 @@ jobs:
         uses: actions/checkout@v4
         with:
           lfs: false
+          ref: ${{ matrix.commits }}
       - name: Extract pr_number from commit message
         id: commit
         run: |
@@ -78,7 +95,7 @@ jobs:
               break
             fi
           done
-          matrix=$(jq -nc '{include: $ARGS.positional | map_values({milestone: .})}' --args "${target_milestones[@]}")
+          matrix=$(jq -nc --argjson milestones "$(printf '%s\n' "${target_milestones[@]}" | jq -R . | jq -s .)" '$milestones')
           echo "matrix=$matrix" >> $GITHUB_OUTPUT
         env:
           GH_TOKEN: ${{ github.token }}
@@ -88,7 +105,8 @@ jobs:
     runs-on: ubuntu-latest
     needs: backport-target-branch
     strategy:
-      matrix: ${{ fromJson(needs.backport-target-branch.outputs.matrix) }}
+      matrix:
+        milestone: ${{ fromJson(needs.backport-target-branch.outputs.matrix) }}
     permissions:
       pull-requests: write
     steps: