ci: fix unspecified version at runtime in docker images (#1903)

Docker images are built with the `vunspecified` version, which comes
because the release step does not use the current [Git context of the
buildx
action](https://github.com/docker/build-push-action?tab=readme-ov-file#git-context):

> Be careful because any file mutation in the steps that precede the
build step will be ignored, including processing of the .dockerignore
file since the context is based on the Git reference. However, you can
use the [Path
context](https://github.com/docker/build-push-action?tab=readme-ov-file#path-context)
using the [context
input](https://github.com/docker/build-push-action?tab=readme-ov-file#inputs)
alongside the [actions/checkout](https://github.com/actions/checkout/)
action to remove this restriction.

.github/workflows/publish.yml

@@ -89,6 +89,7 @@ jobs:
 
       - uses: docker/build-push-action@v3
         with:
+          context: . # IMPORTANT: Dockerfile is modified above to include the release version. Don't remove this line: https://github.com/docker/build-push-action?tab=readme-ov-file#git-context
           push: true
           platforms: linux/amd64,linux/arm64
           tags: ${{ steps.meta.outputs.tags }}