Fix pull request checking condition (#147)

.github/workflows/ack.yml

@@ -27,7 +27,7 @@ jobs:
       # either title, body or source branch name. We ignore potential failure
       # of this step.
       - uses: release-drafter/release-drafter@v5
-        if: ${{ github.event.issue.pull_request }}
+        if: ${{ github.event_name == 'pull_request' }}
         with:
           # we only want to use the auto-labeler bits:
           disable-autolabeler: false
@@ -40,7 +40,7 @@ jobs:
       # Ensure that one of the required labels is present and none of the undesired is absent
       # See https://github.com/jesusvasquez333/verify-pr-label-action
       - name: Verify PR label action
-        if: ${{ github.event.issue.pull_request }}
+        if: ${{ github.event_name == 'pull_request' }}
         uses: jesusvasquez333/[email protected]
         with:
           github-token: "${{ secrets.GITHUB_TOKEN }}"