This PR add several features to release automation:
The existing tag-release job has an output that indicates whether the triggering commit
is a release (i.e. whether it matches the regex)
The new followup job runs a new script which fetches the recent emscripten-releases
revisions, reads the DEPS file from the 'latest' release in emscripten-releases-tags.json
to find the corresponding emscripten revision and writes it into the environment
The final step reads the emscripten revision from the environment and creates a
workflow_dispatch event to run the tag-release.yml job on the emscripten repo
This PR add several features to release automation: