bpo-31177: Skip deleted attributes while calling reset_mock (GH-9302)

(cherry picked from commit edeca92c84a3b08902ecdfe987cde00c7e617887)

Co-authored-by: Xtreak <tirkarthi@users.noreply.github.com>
diff --git a/Lib/unittest/mock.py b/Lib/unittest/mock.py
index b0c03c0..6ba186f 100644
--- a/Lib/unittest/mock.py
+++ b/Lib/unittest/mock.py
@@ -541,7 +541,7 @@
             self._mock_side_effect = None
 
         for child in self._mock_children.values():
-            if isinstance(child, _SpecState):
+            if isinstance(child, _SpecState) or child is _deleted:
                 continue
             child.reset_mock(visited)