remove legacy debugging code from setup.py (#5597)

Author: alex

setup.py

@@ -10,20 +10,9 @@
 import platform
 import sys
 
-import pkg_resources
-
-import setuptools
 from setuptools import find_packages, setup
 
 
-if pkg_resources.parse_version(
-    setuptools.__version__
-) < pkg_resources.parse_version("18.5"):
-    raise RuntimeError(
-        "cryptography requires setuptools 18.5 or newer, please upgrade to a "
-        "newer version of setuptools"
-    )
-
 base_dir = os.path.dirname(__file__)
 src_dir = os.path.join(base_dir, "src")