chore(deps-dev): Bump mypy from 0.800 to 0.812 (openapi-generators#340)

Bumps [mypy](https://github.com/python/mypy) from 0.800 to 0.812.
- [Release notes](https://github.com/python/mypy/releases)
- [Commits](python/mypy@v0.800...v0.812)

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>