Log Message:
lang/janet: Update to 1.28.0

## 1.28.0 - 2023-05-13
- Various bug fixes
- Make nested short-fn's behave a bit more predictably (it is still not
  recommended to nest short-fns).
- Add `os/strftime` for date formatting.
- Fix `ev/select` on threaded channels sometimes live-locking.
- Support the `NO_COLOR` environment variable to turn off VT100 color codes
  in repl (and in scripts).  See http://no-color.org/
- Disallow using `(splice x)` in contexts where it doesn't make sense rather
  than silently coercing to `x`.  Instead, raise a compiler error.
- Change the names of `:user8` and `:user9` sigals to `:interrupt` and
  `:await`
- Change the names of `:user8` and `:user9` fiber statuses to `:interrupted`
  and `:suspended`.
- Add `ev/all-tasks` to see all currently suspended fibers.
- Add `keep-syntax` and `keep-syntax!` functions to make writing macros
  easier.