Fix a regression in permtrace for <2.0a users

A couple bugfixes and minor improvements

2.3.0 - Journey's End

New flag system, jsk exec, jsk invite

Version 2.1.0

- Interactions-based PaginatorInterface implementation for discord.py
  2.0.0a
- JISHAKU_FORCE_PAGINATOR switch (PR scarletcafe#111)
- Support for Discord's relative timestamp markdown

Jishaku 2.0.0 release

Improvements to various commands before v2

- jsk sh performs better on Windows (it now uses PowerShell if
  available, or cmd if not, instead of trying to invoke commands
  directly, making it more like the Linux variant)
- jsk pip added as an alias to jsk sh pip
- jsk selftest adjusted to make more sense on intents versions

Make jsk su perform better on bots that disable the GUILD_MEMBERS intent

Add shim for Task.current_task deprecation in JishakuBase.submit

Add guild_subscriptions info to selftest