Use PR_HEAD_SHA

See docker/metadata-action#414

.github/workflows/build-docker-image.yml

@@ -42,6 +42,8 @@ jobs:
             type=ref,event=branch
             type=ref,event=pr
             type=sha
+        env:
+          DOCKER_METADATA_PR_HEAD_SHA: true
       # This step uses the `docker/build-push-action` action to build the image, based on your repository's `Dockerfile`. If the build succeeds, it pushes the image to GitHub Packages.
       # It uses the `context` parameter to define the build's context as the set of files located in the specified path. For more information, see "[Usage](https://github.com/docker/build-push-action#usage)" in the README of the `docker/build-push-action` repository.
       # It uses the `tags` and `labels` parameters to tag and label the image with the output from the "meta" step.