update stubs for path and creation_date in torrent.pyi

[Ravencentric]

Fixing a couple details I missed:

• path.setter accepts None https://github.com/rndusr/torf/blob/c26f3b3210bba352ca924d7f7ccef7dc89c8c587/torf/_torrent.py#L177-L182
• creation_date property can return None https://github.com/rndusr/torf/blob/c26f3b3210bba352ca924d7f7ccef7dc89c8c587/torf/_torrent.py#L942-L957

[rndusr]

Thanks!

In the future, be sure to fetch any new commits from origin before making a PR. It wasn't really a problem this time, but it can be.

(Although I don't blame you for assuming there won't be any new commits anyway.)

[Ravencentric]

will do! thanks