Ignore missing imports for parameterized. (#11285)

This was due to a conflict between #11282, which changed
mypy configuration, and #11228, a normal change.

changelog.d/11285.misc

+Require all files in synapse/ and tests/ to pass mypy unless specifically excluded.

mypy.ini

@@ -363,6 +363,9 @@ ignore_missing_imports = True
 [mypy-opentracing]
 ignore_missing_imports = True
 
+[mypy-parameterized.*]
+ignore_missing_imports = True
+
 [mypy-phonenumbers.*]
 ignore_missing_imports = True