fix: Pass GH_TOKEN env var to composite action (#994)

The composite action needs GH_TOKEN set as env var.
Use github.token which has the required permissions.

Author: mPokornyETM

.github/workflows/rebase-open-prs.yml

@@ -14,5 +14,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: mPokornyETM/rebase-open-prs-action@v1
+        env:
+          GH_TOKEN: ${{ github.token }}
         with:
-          github-token: ${{ secrets.GH_TOKEN_PAT }}
+          github-token: ${{ github.token }}