chore(deps): bump m-kuhn/backport from 1.2.7 to 1.2.8

Bumps [m-kuhn/backport](https://github.com/m-kuhn/backport) from 1.2.7 to 1.2.8.
- [Release notes](https://github.com/m-kuhn/backport/releases)
- [Commits](m-kuhn/backport@v1.2.7...v1.2.8)

---
updated-dependencies:
- dependency-name: m-kuhn/backport
  dependency-version: 1.2.8
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

.github/workflows/backport.yml

@@ -13,7 +13,7 @@ jobs:
       - name: Backport Bot
         id: backport
         if: github.event.pull_request.merged && ( ( github.event.action == 'closed' && contains( join( github.event.pull_request.labels.*.name ), 'backport') ) || contains( github.event.label.name, 'backport' ) )
-        uses: m-kuhn/backport@v1.2.7
+        uses: m-kuhn/backport@v1.2.8
         with:
           github_token: ${{ secrets.GH_TOKEN_BOT }}