build(deps): bump mypy from 1.19.1 to 1.20.0 in /requirements

Bumps [mypy](https://github.com/python/mypy) from 1.19.1 to 1.20.0.
- [Changelog](https://github.com/python/mypy/blob/master/CHANGELOG.md)
- [Commits](python/mypy@v1.19.1...v1.20.0)

---
updated-dependencies:
- dependency-name: mypy
  dependency-version: 1.20.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

requirements/requirements.txt

@@ -5,5 +5,5 @@ cvxpy == 1.8.1
 ecos == 2.0.14
 pytest == 9.0.2 # For unit test
 pytest-xdist == 3.8.0 # For unit test
-mypy == 1.19.1 # For unit test
+mypy == 1.20.0 # For unit test
 ruff == 0.15.9 # For unit test