Issue #21172: isinstance check relaxed from dict to collections.Mapping.
diff --git a/Misc/NEWS b/Misc/NEWS
index 7756e89..7fef5b5 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -43,6 +43,8 @@
 Library
 -------
 
+- Issue #21172: isinstance check relaxed from dict to collections.Mapping.
+
 - Issue #21191: In os.fdopen, alwyas close the file descriptor when an exception
   happens.