Remove type hinting of slash_command, user_command, message_command

[rpop0]

Summary

This pull request fixes the issue mentioned in #91, specifically slash_command, user_command, message_command decorators caused a "'SlashCommand' object is not callable " warning to appear when being used. This warning is caused due to the return type hinting of the slash_command, user_command and message_command decorators. This pull request removes those return type hinting of the mentioned decorators, fixing issue #91 .

The return type hinting of the mentioned decorators was also redundant, as the docstring attached to them provide an explanation of the return value already.

Checklist

• If code changes were made then they have been tested.
  • I have updated the documentation to reflect the changes.
• This PR fixes an issue.
• This PR adds something new (e.g. new method or parameters).
• This PR is a breaking change (e.g. methods or parameters removed/renamed)
• This PR is not a code change (e.g. documentation, README, ...)

[CodeWithSwastik]

Thanks 👍