ci: give packages/write permission to build container image action

.github/workflows/build-container.yml

@@ -12,7 +12,7 @@ jobs:
     if: github.repository_owner == 'gbdev'
     runs-on: ubuntu-latest
     permissions:
-      contents: write
+      packages: write
     steps:
       - name: Checkout repo
         uses: actions/checkout@v4