Delete python 2 branches from third-party stubs (#7741)

Since #7703, we no longer have third-party stubs that support Python 2, so code like `if sys.version_info >= (3, 0)` can be simplified.

stubs/entrypoints/entrypoints.pyi

@@ -1,13 +1,9 @@
 import sys
 from _typeshed import Self
 from collections.abc import Iterator, Sequence
+from configparser import ConfigParser
 from typing import Any
 
-if sys.version_info >= (3, 0):
-    from configparser import ConfigParser
-else:
-    from ConfigParser import ConfigParser
-
 if sys.version_info >= (3, 8):
     from re import Pattern
 else: