meta: align README/.mailmap/AUTHORS email entries

The email address for Weijia Wang in the AUTHORS and .mailmap files is
different from the email address in the README.md file. Based on their
GitHub profile and commit metadata, the one in the README.md file is the
preferred email. Updating .mailmap and AUTHORS to reflect it.

PR-URL: https://github.com/nodejs/node/pull/39505


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Weijia Wang <starkwang@126.com>