Bump mypy from 0.961 to 0.971 in /requirements (AtsushiSakai#699)

Bumps [mypy](https://github.com/python/mypy) from 0.961 to 0.971.
- [Release notes](https://github.com/python/mypy/releases)
- [Commits](python/mypy@v0.961...v0.971)

---
updated-dependencies:
- dependency-name: mypy
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

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

Author: dependabot[bot]

requirements/requirements.txt

@@ -5,5 +5,5 @@ matplotlib == 3.5.2
 cvxpy == 1.2.1
 pytest == 7.1.2 # For unit test
 pytest-xdist == 2.5.0 # For unit test
-mypy == 0.961 # For unit test
+mypy == 0.971 # For unit test
 flake8 == 4.0.1 # For unit test