build(deps-dev): update mypy requirement from >=1.0.0 to >=1.20.0

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](https://github.com/python/mypy/compare/v1.0.0...v1.20.0)

---
updated-dependencies:
- dependency-name: mypy
  dependency-version: 1.20.0
  dependency-type: direct:development
...

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

pyproject.toml

@@ -18,7 +18,7 @@ dev = [
     # Code quality
     "black>=23.0.0",
     "flake8>=6.0.0",
-    "mypy>=1.0.0",
+    "mypy>=1.20.0",
     # Development utilities
     "pre-commit>=3.0.0",
     # ComfyUI testing (mock dependencies for unit tests)