Update mypy requirement from >=0.971,<1.2 to >=0.971,<1.3

Updates the requirements on [mypy](https://github.com/python/mypy) to permit the latest version.
- [Release notes](https://github.com/python/mypy/releases)
- [Commits](python/mypy@v0.971...v1.2.0)

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

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

Author: dependabot[bot]

pyproject.toml

@@ -48,7 +48,7 @@ djangorestframework = {version = "^3.9", optional = true}
 pytest = "^7.0"
 Sphinx = "^5.0.2"
 sphinx-rtd-theme = "^1.0.0"
-mypy = ">=0.971,<1.2"
+mypy = ">=0.971,<1.3"
 isort = "^5.6.4"
 doc8 = "^0.11.0"
 darglint = "^1.5.7"