use importlib.metadata in minimum_deps

scripts/minimum_deps

@@ -2,6 +2,8 @@
 """
 Generate a requirements-min.txt file based on install_requires
 """
+
+import importlib.metadata
 import json
 import urllib.request
 import warnings
@@ -31,10 +33,14 @@ def get_minimum_version(requirement):
 
 def write_minimum_requirements_file():
     """Write out a requirements-min.txt file for minimum package versions"""
-    dist = pkg_resources.get_distribution('jwst')
+    requirements = [
+        pkg_resources.Requirement.parse(requirement)
+        for requirement in importlib.metadata.distribution('jwst').requires
+        if 'extra' not in requirement
+    ]
 
     with open("requirements-min.txt", "w") as fd:
-        for requirement in dist.requires():
+        for requirement in requirements:
             if requirement.url is None:
                 version = get_minimum_version(requirement)
                 fd.write(f'{requirement.name}=={version}\n')