run CI on python=3.13

[keewis]

• Closes Add python 3.13 to CI #9664

Missing libraries:

• dask: dask-expr depends on pyarrow, which will support 3.13 starting with pyarrow>=18.0
• pydap: depends on webob which uses the removed cgi stdlib (see Resolve Deprecation Warnings  pydap/pydap#319 (comment) in the "out-of-scope" section)
• numba: as usual will take some time to support it (and thus we can't test numbagg and sparse)

[keewis]

Interestingly it's conda that you can't install along with python=3.13, but cftime, pandas, and possibly h5py also raise errors (I can't reproduce that locally, though). So I guess we'll have to revisit this in a couple of weeks.

[mathause]

Is there a reason we are installing conda? For the output of conda info and conda list? There is a micromamba info and micromamba list output in the Setup micromamba step which we could refer to instead.

[keewis]

we use conda to call conda info -a, which contains information micromamba info does not include (and I don't know whether micromamba info -a exists). In theory we could use mamba info -a as well, but that also doesn't provide packages for python 3.13.

[keewis]

does numba support python=3.13 now? If not we're losing some test coverage by not testing on 3.12 (but not sure how important that is?)

[dcherian]

there is an RC out so I guess we wait a little bit more

[max-sixty]

(fwiw unless it's more work — and tests seem to be passing already — I would vote to merge sooner rather than wait on upstream. better to have something working and fewer things in buffer...)