merge for issue #16160: Subclass support now works for types.SimpleNamespace.

diff --cc Misc/NEWS
index aaf07aae4c07b5c69d2754ec224c1e2c195c70cb,944141254f618d2bf7f0226f5c5c985c4b273dda..8efe3860fbb231ad308a95f8f115670752b3da89
--- 1/Misc/NEWS
--- 2/Misc/NEWS
+++ b/Misc/NEWS
@@@ -16,8 -15,8 +16,10 @@@ Core and Builtin
  - Issue #14783: Improve int() docstring and switch docstrings for str(),
    range(), and slice() to use multi-line signatures.
  
+ - Issue #16160: Subclass support now works for types.SimpleNamespace.
+ 
 +- Upgrade Unicode data (UCD) to version 6.2.
 +
  - Issue #15379: Fix passing of non-BMP characters as integers for the charmap
    decoder (already working as unicode strings).  Patch by Serhiy Storchaka.