I've added a PR to update the Python support

[Jonathan Betts]

Hi all,

I've added a PR here which fixes some incompatibilities with 3.9 and adds cross testing across 3.6, 3.7, 3.8 and 3.9.

I'm happy to work with anyone who has the permissions to get this into the project.

Thanks,
Jon Betts
https://web.hypothes.is/

[Jonathan Betts]

Would have been a better comment if I'd added a link to it... oops:

https://github.com/Lawouach/WebSocket-for-Python/pull/269