Update api_version argument to __array_namespace__

[asmeurer]

• Allow 2022.12
• Warn on 2021.12
• Be more strict about only accepting those two versions

[ogrisel]

I am not clear about the current version(s) of the spec implemented by array-api-strict, in particular the README does not seem to have any info about this.

I could not find some of the recently introduced function such as xp.searchsorted so this confirms that it does not yet implement the full v2023.12 it would be great to have a table somewhere that map array-api-strict versions with Array API spec versions and maybe links to one or more tracking issues with the list of things to add/or change before the next versions can of the spec can be considered as supported.

[asmeurer]

Only 2022.12 is currently implemented. You're right that I do need to open a tracking issue for 2023.12 support.