Bump hikari-tanjun from 2.7.0a1 to 2.9.0a1

Bumps [hikari-tanjun](https://github.com/FasterSpeeding/tanjun) from 2.7.0a1 to 2.9.0a1.
- [Release notes](https://github.com/FasterSpeeding/tanjun/releases)
- [Changelog](https://github.com/FasterSpeeding/Tanjun/blob/master/CHANGELOG.md)
- [Commits](Cursed-Solutions/Tanjun@v2.7.0a1...v2.9.0a1)

---
updated-dependencies:
- dependency-name: hikari-tanjun
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

requirements.txt

@@ -6,7 +6,7 @@ hikari==2.0.0.dev112
 hikari-miru==1.1.2
 git+https://github.com/GoogleGenius/plane
 hikari-tanchi==1.3.6
-hikari-tanjun==2.7.0a1
+hikari-tanjun==2.9.0a1
 psutil==5.9.4
 pyright==1.1.280
 toml==0.10.2