Bump black from 21.11b1 to 21.12b0

Bumps [black](https://github.com/psf/black) from 21.11b1 to 21.12b0.
- [Release notes](https://github.com/psf/black/releases)
- [Changelog](https://github.com/psf/black/blob/main/CHANGES.md)
- [Commits](https://github.com/psf/black/commits)

---
updated-dependencies:
- dependency-name: black
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

poetry.lock

@@ -18,7 +18,7 @@ pytest = "^6.2.5"
 pytest-asyncio = "^0.16.0"
 pytest-cov = "^3.0.0"
 mypy = "^0.930"
-black = { version = "^21.11b1", allow-prereleases = true }
+black = { version = "^21.12b0", allow-prereleases = true }
 pre-commit = "^2.16.0"
 unasync-cli = "^0.0.9"