x11-toolkits/hyprtoolkit: Update to 0.5.1

While here, adjust dependency so that libinotify is required only when
system does not yet implement native inotify functions.

Changelog:

• https://github.com/hyprwm/hyprtoolkit/releases/tag/v0.5.0
• https://github.com/hyprwm/hyprtoolkit/releases/tag/v0.5.1

Reported by: GitHub (watch releases)