message: TODO.md update
diff: # RELEASE CHECKLIST
  -- [ ] errors always shown on stderr (no need to explicitly enable via `debug error`)
  -- [ ] Ubuntu PPAs working
  +- [x] errors always shown on stderr (no need to explicitly enable via `debug error`)
  +- [ ] print stack trace upon SEGV
  - [ ] opacity change via shortcut
  - [ ] profile change upon shortcut
  +- [ ] Ubuntu PPAs working
  - [ ] BUG? wrt RenderBuffer: maybe problem with vte emoji asset test? (one emoji)
  - [ ] BUG? hidden scrollbar in alt screen causes render artifacts sometimes?
  - [ ] BUG? eval need of `Terminal::shouldRender` and friends
  