test showing sha ids of commits in github workflow action

.github/workflows/matrix-commit-message.yml

@@ -6,8 +6,8 @@ jobs:
     name: Send message via Matrix
     steps:
       - run: |
-          LAST_MSG=$(git --no-pager show -s --format='%h %an: %s' HEAD)
-          echo '::set-output name=COMMIT_MESSAGE::$LAST_MSG'
+          commits=${{ join(github.event.commits.\*.id, ' ') }}
+          echo '::set-output name=COMMIT_MESSAGE::$commits'
         id: commit-message
       - uses: narodnik/matrix-action@main
         with: