Build Python 3.13 non free threaded using mimalloc

[arnabanimesh]

Build Python 3.13 non free threaded using mimalloc instead of obmalloc/pymalloc

[zanieb]

Can you explain why you would prefer this?

[arnabanimesh]

Main reason: The builds in python.org include mimalloc as mentioned in their release notes.

Also, as a minor sidenote, there is a noticeable (although not that much) speed improvement as mentioned in this thread: python/cpython#90815

[zanieb]

Okay, thanks!

[zanieb]

Please see #391 (comment)

[arnabanimesh]

Oh. Nice.

Although as mentioned in your comment #391 (comment), it is better to mention it explicitly in my opinion. Mentioning the --with-mimalloc flag for non free threaded build is like a test case for ensuring that mimalloc support is indeed present when building using CI. Since we are building free threaded builds (which requires mimalloc) for all the target platforms anyways, we need to ensure that mimalloc is being used for non free threaded builds in those target platforms.

[zanieb]

Yeah I'll probably continue my work there regardless.