bpo-40443: Remove unused imports (GH-25429)

* pyclbr no longer uses copy
* typing no longer uses ast

Issue discovered by pyflakes.

Lib/pyclbr.py

@@ -42,7 +42,6 @@ shouldn't happen often.
 """
 
 import ast
-import copy
 import sys
 import importlib.util
 

Lib/typing.py

@@ -20,7 +20,6 @@ At large scale, the structure of the module is following:
 """
 
 from abc import abstractmethod, ABCMeta
-import ast
 import collections
 import collections.abc
 import contextlib

Misc/NEWS.d/next/Library/2021-04-16-02-03-00.bpo-40443.Io6FHL.rst

@@ -0,0 +1,2 @@
+Remove unused imports: pyclbr no longer uses copy, and typing no longer uses
+ast. Patch by Victor Stinner.