[REF] Replace pkg_resources with distutils and importlib

setup.py

@@ -4,16 +4,20 @@
 """
 
 import sys
+from distutils.version import LooseVersion
+from importlib.metadata import PackageNotFoundError, version
 
-from pkg_resources import VersionConflict, require
 from setuptools import setup
 
 try:
-    require("setuptools>=38.3")
-except VersionConflict:
-    print("Error: version of setuptools is too old (<38.3)!")
+    setuptools_version = LooseVersion(version("setuptools"))
+    required_version = LooseVersion("38.3")
+    if setuptools_version < required_version:
+        print("Error: version of setuptools is too old (<38.3)!")
+        sys.exit(1)
+except PackageNotFoundError:
+    print("setuptools not found")
     sys.exit(1)
 
-
 if __name__ == "__main__":
     setup(use_scm_version=True)