todotxt: Update to 2.12.0

Changes:
2.12.0
------
### Added
- Added default priority variable `TODOTXT_PRIORITY_ON_ADD` ([#246])
- Added `done` option as alias of `do` ([#169])
- Added macOS 10.15.x support ([#300])
- Highlighting of dates, metadata and item numbers ([#264])
- Minimal config file / default filenames (todo.txt, done.txt, report.txt)
  ([#289])
- Enable file completion for add-on actions via `_todo_file{1,2,3}_actions`
  ([#270])
- Allow to customize what can be before / inside / after `+project` and
  `@context` ([#271])

### Changed
- Read the task's name and uses as default ([#249])
- Updated interpreter reference to use environment variable ([#160])
- Allow setting of bash completion path ([#301])

### Fixes
- Fixed no end-of-line bug. Supports todos with no end-of-line. ([#295])

(leot)