Add jishaku.__main__ to setup

[itslychee]

Rationale

Made this change to accurately reflect the entry points of jishaku so toolings such as Nix can accurately detect the console scripts for better packaging.

This simply gives more accurate information about what this package has to offer. There is no real benefit here, just consistency.

Summary of changes made

This adds jishaku.__main__ to entry_points.console_scripts inside setup().

Checklist

• This PR changes the jishaku module/cog codebase
  • These changes add new functionality to the module/cog
  • These changes fix an issue or bug in the module/cog
  • I have tested that these changes work on a production bot codebase
  • I have tested these changes against the CI/CD test suite
  • I have updated the documentation to reflect these changes
• This PR changes the CI/CD test suite
  • I have tested my suite changes are well-formed (all tests can be discovered)
  • These changes adjust existing test cases
  • These changes add new test cases
• This PR changes prose (such as the documentation, README or other Markdown/RST documents)
  • I have proofread my changes for grammar and spelling issues
  • I have tested that any changes regarding Markdown/RST syntax result in a well formed document

[scarletcafe]

Have you tested these changes? I assume click handles it properly, but it also has interesting call signature quirks and you haven't checked anything in the checklist.

[itslychee]

I did not check anything in the checklist because none of them seemed applicable to this PR, also I've tested the change through NixOS/nixpkgs#287864 and you can see the testing below.

(The token has been invalidated)