maint(deps): bump pascalgn/automerge-action from 0.12.0 to 0.15.5

Bumps [pascalgn/automerge-action](https://github.com/pascalgn/automerge-action) from 0.12.0 to 0.15.5.
- [Release notes](https://github.com/pascalgn/automerge-action/releases)
- [Commits](pascalgn/automerge-action@v0.12.0...v0.15.5)

---
updated-dependencies:
- dependency-name: pascalgn/automerge-action
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/pull.yml

@@ -164,7 +164,7 @@ jobs:
           token: ${{ secrets.GITHUB_TOKEN }}
       - name: automerge
         if: ${{env.merge_enabled}} == true
-        uses: 'pascalgn/automerge-action@v0.12.0'
+        uses: 'pascalgn/automerge-action@v0.15.5'
         env:
           GITHUB_TOKEN: '${{ secrets.BOT_TOKEN }}'
           MERGE_LABELS: ${{env.merge_labels}}