fix issue with label-checker (#113)

Error we are facing:
`Error: Check run status and conclusions can only be updated internally
by GitHub Actions. Please see
https://github.blog/changelog/2025-02-12-notice-of-upcoming-deprecations-and-breaking-changes-for-github-actions/#changes-to-check-run-status-modification`

Workaround by using the MCAF token this can be updated again. A proper
solution is in the making here:
danielchabr/pr-labels-checker#18 when that's
implemented we can revert back to the GITHUB_TOKEN.

Author: marwinbaumannsbp

sync-root/.github/workflows/pr-validation.yaml

@@ -86,7 +86,7 @@ jobs:
         id: lint_pr_labels
         with:
           hasSome: breaking,bug,chore,documentation,enhancement,feature,fix,security
-          githubToken: ${{ secrets.GITHUB_TOKEN }}
+          githubToken: ${{ secrets.MCAF_GITHUB_TOKEN }}
 
       - uses: marocchino/sticky-pull-request-comment@v2
         # When the previous steps fails, the workflow would stop. By adding this