dependabot: bump VachaShah/backport from 1.1.4 to 2.2.0 (#515)

Bumps [VachaShah/backport](https://github.com/vachashah/backport) from 1.1.4 to 2.2.0.
- [Release notes](https://github.com/vachashah/backport/releases)
- [Changelog](https://github.com/VachaShah/backport/blob/main/CHANGELOG.md)
- [Commits](VachaShah/backport@v1.1.4...v2.2.0)

---
updated-dependencies:
- dependency-name: VachaShah/backport
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/backport.yml

@@ -22,7 +22,7 @@ jobs:
           installation_id: 22958780
 
       - name: Backport
-        uses: VachaShah/backport@v1.1.4
+        uses: VachaShah/backport@v2.2.0
         with:
           github_token: ${{ steps.github_app_token.outputs.token }}
           branch_name: backport/backport-${{ github.event.number }}