fix: update all occurrences of `discord.py` to `discord.py-self` in `__main__.py`.

[TheOnlyWayUp]

Summary

Fixes #240.

General Info

• [x] If code changes were made then they have been tested.

• [x] This PR fixes an issue (please put issue # in summary).

[dolfies]

Can you rebase this to master?

[dolfies]

Merged manually.