Bump mypy from 1.19.1 to 1.20.1 in /requirements/partial

Bumps [mypy](https://github.com/python/mypy) from 1.19.1 to 1.20.1.
- [Changelog](https://github.com/python/mypy/blob/master/CHANGELOG.md)
- [Commits](python/mypy@v1.19.1...v1.20.1)

---
updated-dependencies:
- dependency-name: mypy
  dependency-version: 1.20.1
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

requirements/partial/requirements_development.txt

@@ -4,7 +4,7 @@ black==26.3.1
 debugpy==1.8.20
 flake8==7.3.0
 isort==8.0.1
-mypy==1.19.1
+mypy==1.20.1
 sqlfluff==4.1.0
 pip-check==3.2.1
 pytest==9.0.3