remove unnecessary import. became unnecessary in https://github.com/dillon-giacoppo/rules_python_external/pull/54/files (#475)

diff --git a/python/pip_install/extract_wheels/lib/namespace_pkgs.py b/python/pip_install/extract_wheels/lib/namespace_pkgs.py
index 82804c5..ca5ffb5 100644
--- a/python/pip_install/extract_wheels/lib/namespace_pkgs.py
+++ b/python/pip_install/extract_wheels/lib/namespace_pkgs.py
@@ -3,8 +3,6 @@
 import textwrap
 from typing import Set, List, Optional
 
-from python.pip_install.extract_wheels.lib import wheel
-
 
 def implicit_namespace_packages(
     directory: str, ignored_dirnames: Optional[List[str]] = None