Do not tag Docker images as latest in PRs (#10)

Author: Schnouki

.github/workflows/docker.yml

@@ -49,7 +49,7 @@ jobs:
           cache-to: type=inline
           tags: |
             ${{ env.IMAGE_NAME }}:${{ env.VERSION }}
-            ${{ env.IMAGE_NAME }}:latest
+            ${{ github.ref == 'refs/heads/main' && github.event_name == 'push' && format('{0}:latest', env.IMAGE_NAME) || '' }}
           platforms: linux/amd64,linux/arm64
 
         env: