Remove fsps from requirements

[troyraen]

Closes #346

[troyraen]

I added the GHA buildhtml label to check whether notebooks still run but that job isn't executing. Tried triggering it manually after adding the label but still no luck. Does it require pushing a new commit after the label has been applied?

[bsipocz]

I think we should instead:

• limit the scikit-build version number as we'll run into this very same problem again when we enable fsps OR
• remove all the new dependencies brought in by that notebook -- so it's all consistent

At minimum we should maybe consider commenting the dependency out with a note that it's temporary and is due to scikit-build. Bottom line, it's OK to do a quick patch to fix up seemingly unrelated failures, but we should make our life easier to reverse it back when the workaround is expected to be needed for a longer period of time (e.g. I don't expect fsps will be new scikit-build compatible any time soon, if ever)

[troyraen]

Sorry, I thought this notebook was never executed based on #315 and that fsps was just left in the requirements file by mistake. Looking closer at the CI config files I see that it is executed in some cases. I'll pin scikit-build-core.

Build is still failing, need to investigate more closely -- the logs of past builds are not very useful for this :(

[bsipocz]

I would think we could add a test job that opts in the SED fitting, but that should be separate from this PR.

[troyraen]

For future reference:

fsps doesn't provide a wheel for python 3.13, so we end up building it from source. This ignores our requirements file and, since their toml doesn't pin scikit-build-core, it picks up latest which fails as of yesterday's scikit-build-core v1.0.0 release.

We could work around that, but we discovered that the OpenUniverse SED notebook doesn't use fsps by default (requires user to change RUN_FITS to True), so there's no need for our testing and deployment infrastructure to install it.

[bsipocz]

Upstream report: dfm/python-fsps#388

(but I think we should stick with python 3.12 for the fsps enabled case)

[troyraen]

Ah, thanks for reporting upstream. Realized I didn't do it while trying to fall asleep last night.