Only push a new Docker image on release (colmap#2436)

.github/workflows/build-docker.yml

@@ -9,6 +9,9 @@ on:
   release:
     types: [ published, edited ]
 
+env:
+  IS_RELEASE: ${{ github.event_name == 'release' || startsWith(github.ref, 'refs/tags') }}
+
 jobs:
   build:
     name: ubuntu-22.04
@@ -23,6 +26,7 @@ jobs:
         uses: docker/setup-buildx-action@v3
 
       - name: Login to Docker Hub
+        if: ${{ env.IS_RELEASE == 'true' }}
         uses: docker/login-action@v3
         with:
           username: ${{ secrets.DOCKERHUB_USERNAME }}
@@ -31,7 +35,7 @@ jobs:
       - name: Build and push
         run: |
           dockertag=$(date +%Y%m%d).${{ github.run_number }}
-          if [[ "${{ github.ref }}" == "refs/heads/main" ]]; then
+          if [[ "${{ env.IS_RELEASE }}" == "true" ]]; then
             cuda_archs="50;60;70;75;90"
           else
             cuda_archs="50"
@@ -41,7 +45,7 @@ jobs:
             --tag colmap/colmap:$dockertag \
             --build-arg COLMAP_GIT_COMMIT="$GITHUB_SHA" \
             --build-arg CUDA_ARCHITECTURES="$cuda_archs"
-          if [[ "${{ github.ref }}" == "refs/heads/main" ]]; then
+          if [[ "${{ env.IS_RELEASE }}" == "true" ]]; then
             docker tag colmap/colmap:$dockertag colmap/colmap:latest
             docker push colmap/colmap:$dockertag
             docker push colmap/colmap:latest