Only run repo-maintenance.yaml on 'commaai/openpilot' (#31401)

This otherwise fails and causes a periodic annoying email for users who have forked the repo.
old-commit-hash: 299dbb564d

.github/workflows/repo-maintenance.yaml

@@ -11,6 +11,7 @@ jobs:
     runs-on: ubuntu-20.04
     container:
       image: ghcr.io/commaai/openpilot-base:latest
+    if: github.repository == 'commaai/openpilot'
     steps:
     - uses: actions/checkout@v4
       with:
@@ -36,6 +37,7 @@ jobs:
     runs-on: ubuntu-20.04
     container:
       image: ghcr.io/commaai/openpilot-base:latest
+    if: github.repository == 'commaai/openpilot'
     steps:
     - uses: actions/checkout@v4
     - name: poetry lock