Update to flake8 3.8.x

In particular this improves support for detecting usage of various
type annotation usages and adds support for correctly parsing
type: ignore comments which contain a reason tag.

setup.cfg

@@ -13,6 +13,8 @@ ignore =
   E721,
   # Line break before binary operator
   W503,
+  # Single letter loop variables are often fine
+  E741,
 exclude = jedi/third_party/* .tox/*
 
 [pycodestyle]

setup.py

@@ -45,7 +45,7 @@ setup(name='jedi',
               'Django<3.1',  # For now pin this.
           ],
           'qa': [
-              'flake8==3.7.9',
+              'flake8==3.8.3',
           ],
       },
       package_data={'jedi': ['*.pyi', 'third_party/typeshed/LICENSE',

test/test_api/test_call_signatures.py

@@ -125,7 +125,7 @@ def test_get_signatures_whitespace(Script):
     abs(
     def x():
         pass
-    """)  # noqa
+    """)
     assert_signature(Script, s, 'abs', 0, line=1, column=5)