clean up the retinotopy/fmriprep submodule installation

[MarieStLaurent]

I do have the retinotopy.fmriprep repo (with_slicetiming branch) installed as a submodule named fmriprep under cneuromod-things/retinotopy, but my install is messy (I made changes to the stimuli sub-submodule that I can't push). Might be simplest to remove and reinstall cleanly.

• I can't see the retinotopy.fmriprep repo on the cneuromod github (is it private?). I worked from the with_slicetiming branch, would it make sense to merge it into main? Or leave it as-is?
• I also can't see the fmriprep/sourcedata/retinotopy submodule which should point to the cneuromod.retinotopy repo on github; my current version on beluga points to a detached head at 1758b9f. Can we validate that this is up-to-date (both the links within the cneuromod-things repo, and the ones between repos on github)?
• Can we also validate that cneuromod.retinotopy contains *events.tsv files under each sub-0*/ses-0*/func folder that contain trialwise metrics? I do have local .tsv files under cneuromod-things/retinotopy/fmriprep/sourcedada/retinotopy, some are local files and other are symbolic links (not sure why).
• Apparently I modified my local fmriprep/sourcedata/retinotopy/stimuli sub-submodule but failed to update the head that the submodule points toward. Might be worth reinstalling fmriprep/sourcedata/retinotopy/ (cneuromod.retinotopy) and making sure its stimuli submodule points to the right branch from retino.stimuli (with the aperture masks).
• Once the nested repo structure (fmriprep/sourcedata/retinotopy/stimuli) is validated on github, perhaps reinstall retinotopy.fmriprep as a submodule called fmriprep under cneuromod-things/retinotopy to replace the old one.