Skip login when the PR is from fork repo

Author: ono-max

.github/workflows/publish.yml

@@ -61,7 +61,7 @@ jobs:
           username: ${{ github.actor }}
           password: ${{ secrets.ACCESS_TOKEN }}
           registry: ghcr.io
-        if: ${{ github.actor != 'dependabot[bot]' }}
+        if: ${{ github.actor != 'dependabot[bot]' && github.event.pull_request.head.repo.fork == false }}
 
       - name: Resolve build_ruby version
         uses: ruby/setup-ruby@7d3497fd78c07c0d84ebafa58d8dac60cd1f0763 # v1.199.0