Restore GitHub PAT for backports

Signed-off-by: Matheus Pimenta <matheuscscp@gmail.com>

Author: matheuscscp

.github/workflows/backport.yaml

@@ -9,4 +9,4 @@ jobs:
       pull-requests: write # for creating pull requests against release branches.
     uses: fluxcd/gha-workflows/.github/workflows/backport.yaml@v0.4.0
     secrets:
-      github-token: ${{ secrets.GITHUB_TOKEN }}
+      github-token: ${{ secrets.BOT_GITHUB_TOKEN }}