Bump pascalgn/automerge-action from 0.15.3 to 0.15.6

Bumps [pascalgn/automerge-action](https://github.com/pascalgn/automerge-action) from 0.15.3 to 0.15.6.
- [Release notes](https://github.com/pascalgn/automerge-action/releases)
- [Commits](pascalgn/automerge-action@v0.15.3...v0.15.6)

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

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

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -75,7 +75,7 @@ jobs:
           app_id: 111016
           private_key: ${{ secrets.BOT_PRIVATE_KEY }}
       - name: automerge
-        uses: pascalgn/automerge-action@v0.15.3
+        uses: pascalgn/automerge-action@v0.15.6
         env:
           GITHUB_TOKEN: "${{ steps.generate_token.outputs.token }}"
           MERGE_LABELS: ""