Update mypy requirement from ==1.3.* to ==1.4.* (#102)

Updates the requirements on [mypy](https://github.com/python/mypy) to permit the latest version.
- [Commits](python/mypy@v1.3.0...v1.4.0)

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

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

requirements-test.txt

@@ -1,4 +1,4 @@
 coverage == 7.2.*
-mypy == 1.3.*
+mypy == 1.4.*
 pre-commit == 3.3.*
 tox == 4.6.*