Update ubuntu version for RTD builds

[weaverba137]

Read the Docs (RTD) has announced that ubuntu-20.04 is being deprecated see this post for details. This PR sets ubuntu-lts-latest which should currently correspond to ubuntu-26.04.

When I get a chance I'll try to trigger a RTD build on this branch to test.

[weaverba137]

@dylanagreen I don't think I have maintainer status for QuasarNB on ReadTheDocs. Could you please set that up? My RTD id is the same as GitHub.

[dylanagreen]

@weaverba137 Thanks for doing this. I got the email from RTD this morning and had it on my todolist to update, but you beat me to it! I've just added you as a maintainer on RTD.

[weaverba137]

Build succeded. However some warnings turned up during the Sphinx build that need to be addressed. Let me try to fix those before merging.

[weaverba137]

It turns out that quasarnp.utils has some module-level computations that are being run at import time, and these will fail if NumPy is not installed, which it might not be in a RTD environment. Is there any way we can move those module-level computations into a function?

[weaverba137]

@dylanagreen could please take a look my previous question when you get a chance?

[dylanagreen]

Thanks for the reminder @weaverba137. I think it is possible to move the computations to a function. The only computations that are done (that I can recall) are the ones that compute the wavelength grid (I think they're just np.arange or linspaces). Should be able to move them to a function that gets called on occasion. Let me work on that in the next day or so.

[weaverba137]

Thank you for looking in to this. I should also say that it isn't necessary to implement anything specifically for this pull request, it could be done separately.

[dylanagreen]

Sorry this has taken so long @weaverba137, I got sick shortly after committing to look at this and then it fell off myplate again. But I have given it some thought and I think the best path is to move the module level calculations into a Class/Object that gets passed around. It's a refactor that will take a little bit of work to make sure things are interop-ing correctly, but that I can try do this week. This way those module level calls are only called when an object is instantiated rather than the module imported.

Since you said that it's not a blocking factor for this PR, if there's no objections I will merge this PR so we can clear it off our plates while I work on the minor refactor. Does that work?

[weaverba137]

@dylanagreen, yes, we can merge this PR and then you can work on the refactor separately. Note that the RTD configuration updated by this PR does install NumPy in the RTD environment, so the documentation does work.