Update allsky.sh
Update allsky.sh

* Improve way we determine if libcamera or raspistill should be used with RPiHQ cameras.  If the `libcamera-still` command exists and works we'll use libcamera, otherwise we'll use raspistill.  It doesn't matter what OS the user is on.
thomasjacquin/allsky,thomasjacquin/allsky,thomasjacquin/allsky