Switch to `python -m build`.

`python setup.py` has been deprecated for years, apparently.

Change-Id: Ibebd81dd4d1531fe6b689dc0499c04511286473a
Reviewed-on: https://code-review.googlesource.com/c/re2/+/61831
Reviewed-by: Paul Wankadia <junyer@google.com>
Reviewed-by: Perry Lorier <perryl@google.com>
1 file changed