ci(github): add contents permission for buildpack branch sync (#1092)

Author: douglasduteil

.github/workflows/buildpack.yml

@@ -12,6 +12,8 @@ jobs:
   push:
     name: Sync scalingo/buildpack branch with .scalingo/buildpack folder
     runs-on: ubuntu-latest
+    permissions:
+      contents: write
     steps:
       - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
       - uses: peaceiris/actions-gh-pages@4f9cc6602d3f66b9c108549d475ec49e8ef4d45e # v4.0.0