ENH: Backport free-threading support to 2.3

[crusaderky]

Follow-up from #59057

When I import the pandas-2.3.1 wheel from pypi in Python 3.13t, I get

E RuntimeWarning: The global interpreter lock (GIL) has been enabled to load module 'pandas._libs.pandas_parser', which has not declared that it can run safely without the GIL. To override this behavior and keep the GIL disabled (at your own risk), run with PYTHON_GIL=0 or -Xgil=0.

Additionally, there are no conda-forge packages at all for 2.3.1 3.13t.

Nightly 2.4 wheels (https://pypi.anaconda.org/scientific-python-nightly-wheels/simple) work as expected.

Environment

Linux x86_64

[rhshadrach]

Assuming #59057 is complete, it would be helpful to understand the set of PRs that would need to be backported to support this. While no strong objection assuming the changes are small, I think I'd still prefer to just release 3.0 which hopefully will not be a long wait.

cc @mroeschke

[mroeschke]

Yeah I've lost track of the various PRs associated with #59057, but I would also be more comfortable waiting for pandas 3.0 (hopefully in a few months) instead of backporting all the free threading changes