Add furo theme to pyopenms.readthedocs.io

[tapaswenipathak]

Ref:

• https://discord.com/channels/832282841836159006/969233556788359228/983993758980911144
• https://github.com/OpenMS/pyopenms-docs/issues/293
• https://github.com/pradyunsg/furo/issues/79#issuecomment-774428681

Fixes https://github.com/OpenMS/pyopenms-docs/issues/284.

[tapaswenipathak]

cc @tjeerdijk @jpfeuffer.

[tapaswenipathak]

Options:

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Another one with 🚀:

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[jpfeuffer]

Unfortunately, the discussion in #339 was never finished. I don't think Furo is the best theme for us anymore. No good version selection, announcement banner for "launch in binder" is a bad hack.

The pydata theme is IMHO a much better fit. https://github.com/pydata/pydata-sphinx-theme

[jpfeuffer]

Ok, that looks better. I am a bit worried about the maintenance of the heavily modified internals of the underlying theme. I'll leave it up to others to decide if we use this theme with these addons or use a theme that actively supports what we need. @timosachsenberg @poshul @tjeerdijk @greengypsy