BUG: for whatever reason, the Salzinnes folios are now off by 6 and need to be remapped

Steps to reproduce:
- Go here: https://cantus.simssa.ca/manuscript/123723/
- Click on "go to first chant"
- The folio number will say "001r"
- The chants loaded will be chants on the page you're looking at
- the page is 008r, not 001r

I have no idea how or when this happened. When I tested following the diva6 update things worked. At some point since then, something happened to the data. There is a folio mapping script floating in the cantus repo somewhere that might fix this, but a more permanent fix or test would be ideal.