chore(deps-dev): update mypy requirement from >=1.14 to >=1.20.2 in /sdk

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@v1.14.0...v1.20.2)

---
updated-dependencies:
- dependency-name: mypy
  dependency-version: 1.20.2
  dependency-type: direct:development
...

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

Author: dependabot[bot]

sdk/pyproject.toml

@@ -32,7 +32,7 @@ dev = [
     "pytest>=9.0.3",
     "pytest-cov>=6.0",
     "pytest-asyncio>=1.3.0",
-    "mypy>=1.14",
+    "mypy>=1.20.2",
     "mypy-protobuf>=3.6",
     "ruff>=0.15.12",
     "grpcio-tools>=1.80.0",