Bump minimum Python version to 3.11

[tsbinns]

Fixes #14138

This is what I found from git grep '3\.10' -- ':!doc/_static/*' ':!mne/io/egi/tests/data/*' ':!mne/channels/data/*' ':!mne/report/js_and_css/*' and git grep 'TODO VERSION'

[tsbinns]

pip-pre failure fixed in #14139

[tsbinns]

scipy build was failing due to missing openblas (https://github.com/mne-tools/mne-python/actions/runs/31031975809/job/92394959899) which I've tried to resolve, but is now taking ages to build (https://github.com/mne-tools/mne-python/actions/runs/31033937498/job/92401198303?pr=14140).

Is this an issue with the cache needing to be rebuilt due to the Python ver getting bumped, and after that it will be fine, or do we need to find a way around building from source?

[larsoner]

SciPy shouldn't even try to build from source, we should be passing an --only-binary that prevents it. This seems like some bug with SciPy's nightly, or some other dependency requiring some version of SciPy that doesn't have wheels, or something. @tsbinns you want to look further or need help?

[tsbinns]

I'll try to have another crack at it

[tsbinns]

Hadn't updated the 'old' CI lockfile 🤦🏻