2024 Upgrade TODOs, nice-to-haves, etc

[esoterik]

This is intended to be a meta issue to capture any other additional issues or possible improvements that come up while upgrading, just so nothing gets lost.

TODOs

Minimum

• [x] No security warnings from dependency versions
• [x] Upgrade rubocop
• [x] Upgrade sentry

Higher priority but not mandatory

• [x] Migrate from kt-paperclip to carrierwave

Stretch goals

• [x] Upgrade to Rails 7.0
• [ ] Migrate asset pipeline away from rails-assets gems to importmaps

Bugs

Nice-to-haves

• [x] Remove database cleaner per this comment
• [ ] Fix admin html so that labels are properly associated with their fields (see this comment in creation specs)