Fix: make registry login conditional inside step instead of using if: on step

.gitea/actions/docker-build/action.yml

@@ -113,9 +113,10 @@ runs:
 
     - name: Log in to Docker registry
       shell: bash
-      if: inputs.push == 'true' && inputs.registry != ''
       run: |
-        echo "${{ inputs.registry-password }}" | docker login ${{ inputs.registry }} -u ${{ inputs.registry-username }} --password-stdin
+        if [ -n "${{ inputs.registry }}" ] && [ -n "${{ inputs.registry-password }}" ]; then
+          echo "${{ inputs.registry-password }}" | docker login ${{ inputs.registry }} -u ${{ inputs.registry-username }} --password-stdin || echo "Login failed or not needed"
+        fi
 
     - name: Build image
       id: build