Release v4.0.0

[NSeydoux]

This PR bumps the version to v4.0.0.

Checklist

• I inspected the changelog to determine if the release was major, minor or patch. I then used the command npm version <major|minor|patch> to update the package.json and package-lock.json (and locally create a tag).
• The CHANGELOG has been updated to show version and release date - https://keepachangelog.com/en/1.0.0/.
• @since X.Y.Z annotations have been added to new APIs.
• The only commits in this PR are:
  • the CHANGELOG update.
  • the version update.
  • @since annotations.
• I will make sure not to squash these commits, but rebase instead.
• Once this PR is merged, I will push the tag created by npm version ... (e.g. git push origin vX.Y.Z).