* Publish GitHub release from master branch
This ensures that changes made on `develop` since branching for the
release are not included. It also ensures that the final release
sourcemaps line-up correctly (they were always build on master)`.
* Consolidate publish jobs
The jobs `job-publish-release` and `create_github_release` both handle
different parts of publishing a release. They have been consolidated
into a single `job-publish-release` job.
* Update release script to expect a merge commit
The release script was originally written to be run on `develop`, so it
expected the current commit to be a result of `Squash & Merge`. Now
that it's run on `master`, it will generally be run against a merge
commit.
The version is now extracted from the commit message using a regular
expression that should work on all version of Bash v3+, and should be
tolerant of both merge commits and `Squash & Merge` commits.
* Target `master` with release PR
`master` is now targeted by the release PR instead of `develop`, as
the release has to be created from the master branch.
The update to `develop` is handled after the release by a PR from
`master` to `develop`, which is created automatically after the
release.
