Missing license information on PYPI

[Yuxuan Lu]

There is no license information for ypy and ypy-websocket on pypi.

Other packages:

y-py:

This is blocking our company's auto-build system. I would appreciate it if you could fill in your license in pypi.

[David Brochart]

Thanks for reporting @leoleoasd, do you want to open a PR?

[David Brochart]

Fixed in #123.