Chore(deps-dev): Update mypy requirement from <1.19 to <1.20

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@v0.1.0...v1.19.1)

---
updated-dependencies:
- dependency-name: mypy
  dependency-version: 1.19.1
  dependency-type: direct:development
...

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

Author: dependabot[bot]

pyproject.toml

@@ -55,7 +55,7 @@ dependencies = [
 dev = [
     "certifi>=2025.10.5",
     "coverage<8",
-    "mypy<1.19",
+    "mypy<1.20",
     "poethepoet<1",
     "pytest<10",
     "pytz>=2025.2",

setup.py

@@ -68,7 +68,7 @@ def read(path):
             'backports.zoneinfo<1; python_version<"3.9"',
             "certifi",
             "createcoverage>=1,<2",
-            "mypy<1.18",
+            "mypy<1.20",
             "poethepoet<1",
             "ruff<0.15",
             "stopit>=1.1.2,<2",