Make the validation test for entry-points work with Python 3.13+

The exception in importlib.metadata has changed.
See python/importlib_metadata#488

This makes an existing test pass with Python 3.13.

Partially fixes pypa#4196

setuptools/_entry_points.py

@@ -17,7 +17,8 @@ def ensure_valid(ep):
     """
     try:
         ep.extras
-    except AttributeError as ex:
+    except (AttributeError, AssertionError) as ex:
+        # Why both? See https://github.com/python/importlib_metadata/issues/488
         msg = (
             f"Problems to parse {ep}.\nPlease ensure entry-point follows the spec: "
             "https://packaging.python.org/en/latest/specifications/entry-points/"