Added support for creating and joining voice channels

[Filip3314]

While testing my bot, I ran into issues because some of its functionality relies on joining/leaving voice channels or checking the voice state of users. To remedy this, I've implemented the FakeVoiceChannel and FakeVoiceClient classes, in addition to creating a callback for edit_member and expanded the create_channel method to cover voice channels. I've included some tests for the new feature.

Please let me know if you think there's anything missing or incorrect in my PR. Thanks!

[Sergeileduc]

Sounds good (I didn't have time to checkout out and test, but it sounds good)

Just a typo.

also, if you could rebase, in order to have less commits (and make a new PR when it's done) ?
it's not super important, if you can't, it's okay, don't worry.

[Filip3314]

Hey, thanks for taking a look at the PR. I can rebase and make a new one, no problem.
About the typo, could you tell me where it is so I could fix it?

[Sergeileduc]

ho you don't see my review ? didn't know.

yeah it's in tests/test_permissions.py line 34

administrator is misspelled

[Sergeileduc]

ho you don't see my review ? didn't know.

yeah it's in tests/test_permissions.py line 34

administrator is misspelled

@Filip3314

[Filip3314]

Okay, rebased and squashed all the commits into one. Fixed the typo as well. Let me know if there's anything else I need to do!