Fix Docker login step condition placement

Author: GeiserX

.github/workflows/main.yml

@@ -77,6 +77,7 @@ jobs:
         registry: ${{ env.REGISTRY }}
         username: ${{ secrets.DOCKER_USERNAME }}
         password: ${{ secrets.DOCKER_TOKEN }}
+      if: github.event_name != 'pull_request'
 
     - name: Extract metadata
       id: meta