Pin mypy-zope for compatibility with mypy. (#8600)

changelog.d/8600.misc

+Update `mypy` static type checker to 0.790.

setup.py

@@ -102,7 +102,7 @@ CONDITIONAL_REQUIREMENTS["lint"] = [
     "flake8",
 ]
 
-CONDITIONAL_REQUIREMENTS["mypy"] = ["mypy==0.790", "mypy-zope"]
+CONDITIONAL_REQUIREMENTS["mypy"] = ["mypy==0.790", "mypy-zope==0.2.8"]
 
 # Dependencies which are exclusively required by unit test code. This is
 # NOT a list of all modules that are necessary to run the unit tests.