Skip needless login action for docker registry

Author: hsbt

.github/workflows/build_multiarch.yml

@@ -133,12 +133,14 @@ jobs:
       with:
         username: ${{ secrets.DOCKER_USER }}
         password: ${{ secrets.DOCKER_PASS }}
+      if: ${{ matrix.registry_name == 'rubylang' }}
 
     - uses: docker/login-action@v3
       with:
         registry: ghcr.io
         username: ${{ secrets.GHCR_USER }}
         password: ${{ secrets.GHCR_ACCESS_TOKEN }}
+      if: ${{ matrix.registry_name == 'ghcr.io/ruby' }}
 
     - name: Create manifest for ${{ matrix.registry_name }}
       run: |-