Retrieve PR's for commits from new GitHub API

[rwjblue]

GitHub introduced a new API for determining which PR a commit came from, we could use this API to avoid the multiple regular expression matchers that we are having to use today (e.g. the "squash and merge" style, the "merge commit" style, "homu", etc).

References:

• API documentation for the new endpoint
• Blog Post

[simonihmig]

This seems very useful, to make the detection stable.

I just played around with my IDE's (JetBrains) ability to interact with the Github APIs, in this case reviewing and merging a PR. Apparently it caused the merge commit to have a different message than usual:

The from part is missing from this regex, so didn't get any changelog information...

[thibaultdalban]

Could it allow to use lerna-changelog with PRs rebased and not only merged or squashed?