Update mypy requirement from ^0.991 to ^1.2

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@v0.991...v1.2.0)

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

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

pyproject.toml

@@ -17,7 +17,7 @@ pytest-cov = "^4.0.0"
 codecov = "^2.1.12"
 black = "^22.1"
 isort = "^5.9.3"
-mypy = "^0.991"
+mypy = "^1.2"
 Sphinx = "^5.3.0"
 sphinx-autobuild = "^2021.3.14"
 sphinx-copybutton = "^0.5.0"