Python 3.13 added a new DeprecationWarning which is triggered when

calling setattr() to replace the code object of a function in the case

that the code object's flags have a mismatch on the CO_GENERATOR,

CO_COROUTINE, or CO_ASYNC_GENERATOR bits. This was done in response

to a bug (https://github.com/python/cpython/issues/81137) where

replacing a lambda's code object with the gi_code attribute from a

generator expression would then cause cpython to crash. This was purely

a problem with the way that gi_code works for generator expressions

(and comprehensions), and does not affect generator functions in the

same way. This means that rather than posing a real issue for kgb, we

just see ugly warnings.
In order to prevent these warnings, we now copy true values for those

three flags from the old code object into the new one.

Commented out the fix and saw the new unit test fail.
Ran unit tests and saw no more warnings.
Tested with an experimental test (not included here) that replaces an

  async generator and saw that that worked too.
Ran tests on Python 3.8-3.13