protect docker actions on pull requests

.github/workflows/docker-latest.yml

@@ -21,6 +21,7 @@ jobs:
         run: sbt assembly
 
       - name: Login to Docker Hub
+        if: github.event_name != 'pull_request'
         uses: docker/login-action@v1
         with:
           username: ${{ secrets.DOCKER_HUB_USERNAME }}
@@ -36,8 +37,8 @@ jobs:
         with:
           context: ./
           file: ./Runner.Dockerfile
-          push: true
           tags: librecaptcha/lc-core:latest
+          push: ${{ github.event_name != 'pull_request' }}
 
       - name: Image digest
         run: echo ${{ steps.docker_build.outputs.digest }}