Bump SPHT to v0.22 + adopt new syntax for applicable shortcodes

[agriyakhetarpal]

This PR bumps the theme to the new v0.22 release, adapting new syntax for figure, image, and button shortcodes via scientific-python/scientific-python-hugo-theme#674. This is building upon @goanpeca's work in #648. Closes #648.

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[stefanv]

Who on this repo has access to the SciPy Netlify settings? We need to update the build image to the latest version for this to pass.

[melissawm]

Gentle ping to maintainers, does anyone know who could update the netlify image?

[stefanv]

Sorry, this is me talking to myself—apparently, I missed that I have access to these accounts.

[stefanv]

OK, image has been updated.

[agriyakhetarpal]

All green! I manually checked a few pages of the deployment and I don't see any major problem.

[melissawm]

Checked all the pages, all looks good. Thanks @agriyakhetarpal and @stefanv !

[melissawm]

Any objections to merging this, folks? If not, I'm just going to push the button soon!

[agriyakhetarpal]

@melissawm it would be good to merge! FYI, @stefanv and I have a few PRs planned for another v0.23 release, so this PR will only help advance them (the theme builds scipy.org from the main branch, which is not ideal when we introduce breaking changes; perhaps we should change that).

[melissawm]

Ok let's do it - thanks folks!