Bump tjenkinson/gh-action-auto-merge-dependency-updates

Bumps [tjenkinson/gh-action-auto-merge-dependency-updates](https://github.com/tjenkinson/gh-action-auto-merge-dependency-updates) from 4d7756c04d9d999c5968697a621b81c47f533d61 to 20bd740016ca0cf902cfdd994aaabe2a78d3bed5.
- [Release notes](https://github.com/tjenkinson/gh-action-auto-merge-dependency-updates/releases)
- [Commits](tjenkinson/gh-action-auto-merge-dependency-updates@4d7756c...20bd740)

---
updated-dependencies:
- dependency-name: tjenkinson/gh-action-auto-merge-dependency-updates
  dependency-type: direct:production
...

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

.github/workflows/automerge-dependencies.yml

@@ -36,7 +36,7 @@ jobs:
       }}
     runs-on: ubuntu-latest
     steps:
-      - uses: tjenkinson/gh-action-auto-merge-dependency-updates@4d7756c04d9d999c5968697a621b81c47f533d61
+      - uses: tjenkinson/gh-action-auto-merge-dependency-updates@20bd740016ca0cf902cfdd994aaabe2a78d3bed5
         with:
           repo-token: ${{ secrets.GITHUB_TOKEN }}
           allowed-actors: dependabot[bot]