Bump black from 21.6b0 to 21.7b0

Bumps [black](https://github.com/psf/black) from 21.6b0 to 21.7b0.
- [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

@@ -39,7 +39,7 @@ Django = { version = "<3.3.0", optional = true}
 pytest = "^6.2"
 pytest-cov = "^2.12.1"
 pytest-asyncio = "^0.15.1"
-black = "^21.6b0"
+black = "^21.7b0"
 pre-commit = "^2.13.0"
 Faker = "^8.10.1"
 requests = "^2.26.0"