Update mypy to the latest

This includes updating the ignore comments for things which mypy
now knows about or now complains about, as well as pulling in some
typeshed packages for things outside the standard library.

setup.py

@@ -45,7 +45,10 @@ setup(name='jedi',
           ],
           'qa': [
               'flake8==3.8.3',
-              'mypy==0.782',
+              # latest version supporting Python 3.6
+              'mypy==0.971',
+              # Arbitrary pins, latest at the time of pinning
+              'types-setuptools==67.2.0.1',
           ],
           'docs': [
               # Just pin all of these.