- Fix diagnostics for the new `vim.diagnostic` feature. Currently only
  enabled for people using Neovim v0.6.
- Support displaying hint labels as uppercase. This doesn’t change
  anything to the actual key you have to press on your keyboard; it is
  just a visual help.
- Support falling back to 1-char mode when pressing a special key in
  2-char mode. That key is optional and configured in the user
  configuration.