.github: Bump korthout/backport-action from 4.6.1 to 4.7.0

Bumps [korthout/backport-action](https://github.com/korthout/backport-action) from 4.6.1 to 4.7.0.
- [Release notes](https://github.com/korthout/backport-action/releases)
- [Commits](6b65649031...8560fb503c)

---
updated-dependencies:
- dependency-name: korthout/backport-action
  dependency-version: 4.7.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

.github/workflows/backport.yml

@@ -51,7 +51,7 @@ jobs:
 
       - name: Create backport PRs
         id: backport
-        uses: korthout/backport-action@6b65649031ac6d18ffdfd0c0820e9436f3fde22b # v4.6.1
+        uses: korthout/backport-action@8560fb503c275d433c56f05a2f64850093baa9f7 # v4.7.0
         with:
           # Config README: https://github.com/korthout/backport-action#backport-action
           add_author_as_reviewer: true