bpo-40077: Convert _pickle module to use heap types.

[CharlieZhao95]

Replace statically allocated types in _pickle module with heap allocated types:
use PyType_FromModuleAndSpec().

https://bugs.python.org/issue40077

[vstinner]

Sadly, for now, converting static types to heap types is stale: https://bugs.python.org/issue40077#msg411630

[CharlieZhao95]

Sadly, for now, converting static types to heap types is stale: https://bugs.python.org/issue40077#msg411630

Thanks for your reply! I'll keep this branch around and await to get permission from SC to continue with these changes.

[erlend-aasland]

FYI: python/steering-council#99

[kumaraditya303]

FYI: python/steering-council#99

@erlend-aasland What is the current status now? Should more extension modules be ported or not ?

[erlend-aasland]

Petr and I are working on a PEP. When it is ready for review, we'll post it on Discourse/python-dev. When all comments have been addressed, we'll submit it to the SC and wait for either acceptance or rejection. I don't think there will be a change of status in the 3.11 development frame.