fix NIFTy 5 ASCL citation
Probably got mangled in the 5 -> 6 rename.
Citation fixup, no functional changes.
We’ve updated our runner tagging system. If you’re using our shared runners for your CI pipelines, please review the new tags here: https://docs.mpcdf.mpg.de/bnb/220.html#new-tags-for-mpcdf-gitlab-runners
The old tags will remain valid until the end of February 2026.
Probably got mangled in the 5 -> 6 rename.
Citation fixup, no functional changes.