Adding pull-requests right

Adding pull-requests right according to https://gitlab.eclipse.org/eclipsefdn/helpdesk/-/issues/3996

Author: ghentschke

.github/workflows/licensecheck.yml

@@ -18,4 +18,6 @@ jobs:
     with:
       projectId: tools.cdt
     secrets:
-      gitlabAPIToken: ${{ secrets.GITLAB_API_TOKEN }}
+      gitlabAPIToken: ${{ secrets.GITLAB_API_TOKEN }}
+    permissions:
+      pull-requests: write