gh-121604: Make sure all deprecated items in importlib raise DeprecationWarning (#128007)

Co-authored-by: rashansmith <smith.rashan@gmail.com>
Co-authored-by: Stan Ulbrych <89152624+StanFromIreland@users.noreply.github.com>
Co-authored-by: Brett Cannon <brett@python.org>

Lib/importlib/_bootstrap_external.py

@@ -716,6 +716,12 @@ class WindowsRegistryFinder:
 
     @classmethod
     def find_spec(cls, fullname, path=None, target=None):
+        _warnings.warn('importlib.machinery.WindowsRegistryFinder is '
+                       'deprecated; use site configuration instead. '
+                       'Future versions of Python may not enable this '
+                       'finder by default.',
+                       DeprecationWarning, stacklevel=2)
+
         filepath = cls._search_registry(fullname)
         if filepath is None:
             return None