Update secret name

Signed-off-by: Bryan Ramos <bramos@redhat.com>

Author: CryptoRodeo

.github/workflows/cleanup-prs.yml

@@ -18,7 +18,7 @@ jobs:
     steps:
       - name: Close PRs for release-* branches
         env:
-          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          GH_TOKEN: ${{ secrets.GH_TOKEN }}
         run: |
           echo "Finding open PRs that are for release branches"