workflows/backport: bump korthout/backport-action from 4.1.0 to 4.2.0

Bumps [korthout/backport-action](https://github.com/korthout/backport-action) from 4.1.0 to 4.2.0.
- [Release notes](https://github.com/korthout/backport-action/releases)
- [Commits](https://github.com/korthout/backport-action/compare/01619ebc9a6e3f6820274221b9956b3e7365000a...4aaf0e03a94ff0a619c9a511b61aeb42adea5b02)

---
updated-dependencies:
- dependency-name: korthout/backport-action
  dependency-version: 4.2.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

.github/workflows/backport.yml

@@ -49,7 +49,7 @@ jobs:
 
       - name: Create backport PRs
         id: backport
-        uses: korthout/backport-action@01619ebc9a6e3f6820274221b9956b3e7365000a # v4.1.0
+        uses: korthout/backport-action@4aaf0e03a94ff0a619c9a511b61aeb42adea5b02 # v4.2.0
         with:
           # Config README: https://github.com/korthout/backport-action#backport-action
           copy_labels_pattern: 'severity:\ssecurity'