chore(deps): update dependency mypy to v1.20.0

Author: renovate[bot]

pyproject.toml

@@ -66,7 +66,7 @@ types = [
   "django-stubs-ext==6.0.2",
   "django-stubs[compatible-mypy]==6.0.1",
   "djangorestframework-stubs==3.16.9",
-  "mypy==1.19.1",
+  "mypy==1.20.0",
   "PyGObject-stubs==2.17.0",
   "types-dateparser==1.4.0.20260328",
   "types-docutils==0.22.3.20260322",