Update mypy requirement from ==1.15.* to ==1.16.*

Updates the requirements on [mypy](https://github.com/python/mypy) to permit the latest version.
- [Changelog](https://github.com/python/mypy/blob/master/CHANGELOG.md)
- [Commits](python/mypy@v1.15.0...v1.16.0)

---
updated-dependencies:
- dependency-name: mypy
  dependency-version: 1.16.0
  dependency-type: direct:production
...

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

Author: dependabot[bot]

requirements-test.txt

@@ -1,5 +1,5 @@
 coverage == 7.6.*
-mypy == 1.15.*
+mypy == 1.16.*
 pre-commit == 4.1.*
 pytest == 8.3.*
 pytest-cov == 6.0.*