Update mypy requirement from ==1.18.* to ==1.19.*

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@v1.18.1...v1.19.0)

---
updated-dependencies:
- dependency-name: mypy
  dependency-version: 1.19.0
  dependency-type: direct:production
...

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

Author: dependabot[bot]

requirements-test.txt

@@ -2,7 +2,7 @@ black==25.11.*
 flake8==7.3.*
 isort==7.0.*
 moto[server,kms]==5.1.*
-mypy==1.18.*
+mypy==1.19.*
 pytest==9.0.*
 pytest-asyncio==1.3.*
 pytest-cov==7.0.*