Replace typing.List with list and others

https://docs.python.org/3.9/whatsnew/3.9.html#pep-585-builtin-generic-types

Python 3.9 (and Python 3.7 if you do from __future__ import annotations) will let you write

from typing import List

def a(my_arg: List) -> List:
    return []

as

def a(my_arg: list) -> list:
    return []

Same goes for typing.Dict and a bunch of others, see https://www.python.org/dev/peps/pep-0585/

[jdufresne]

Perhaps another example of the same idea, replace typing.Text with str for --py3-plus.

Example input:

if False:
    from typing import Text


def f():
    # type: () -> Text
    return "hello"

Example diff:

--- before.py
+++ after.py
@@ -3,5 +3,5 @@
 
 
 def f():
-    # type: () -> Text
+    # type: () -> str
     return "hello"

[asottile]

via #371