gh-103193: Fix refleaks in `test_inspect` and `test_typing` (#104320)

Lib/test/libregrtest/utils.py

@@ -210,6 +210,13 @@ def clear_caches():
     else:
         fractions._hash_algorithm.cache_clear()
 
+    try:
+        inspect = sys.modules['inspect']
+    except KeyError:
+        pass
+    else:
+        inspect._shadowed_dict_from_mro_tuple.cache_clear()
+
 
 def get_build_info():
     # Get most important configure and build options as a list of strings.