Skip login when the PR is from fork repo

Author: ono-max

.github/workflows/publish.yml

@@ -60,7 +60,7 @@ 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@c04af2bb7258bb6a03df1d3c1865998ac9390972 # v1.194.0