Fix an error when loading namespace packages

Fixes #25

Refs. plone/Products.CMFPlone#4126

news/25.bugfix.rst

@@ -0,0 +1 @@
+Fix an error when loading namespace packages. [ale-rt]

src/plone/autoinclude/loader.py

@@ -1,4 +1,3 @@
-from pkg_resources import iter_entry_points
 from pkg_resources import resource_filename
 from pkg_resources import working_set
 from zope.configuration.xmlconfig import include
@@ -37,14 +36,16 @@ def load_z3c_packages(target=""):
     This returns a dictionary of package names and packages.
     """
     dists = {}
-    for ep in iter_entry_points(group="z3c.autoinclude.plugin"):
+
+    for ep in importlib.metadata.entry_points(group="z3c.autoinclude.plugin"):
         # If we look for target 'plone' then only consider entry points
         # that are registered for this target (module name).
         # But if the entry point is not registered for a specific target,
         # we can include it.
-        if target and ep.module_name != target:
+        module_name = ep.dist.name
+        if target and module_name != target:
             continue
-        module_name = ep.dist.project_name.replace("-", "_")
+
         if module_name not in _known_module_names:
             try:
                 dist = importlib.import_module(module_name)