Remove mypy exclude pattern (#856)

Author: emontnemery

mypy.ini

@@ -19,6 +19,3 @@ disallow_untyped_decorators = true
 disallow_untyped_defs = true
 warn_return_any = true
 warn_unreachable = true
-exclude = (?x)(
-    ^pychromecast/generated/ # The protobuf autogenerated files are not annotated
-  )