Not sure if this works for Lawrence37’s auto generated image, but GitHub has a Watch functionality:
Set that to All Activity will probably get you notified. Then again; It will notify you of everything…
As you can see mine is set to Custom (and then to Releases, but this only notifies you of official, stable releases.
Alternatively you could write a small script that runs via crontab.
You can run rawtherapee -v to get the version you are currently running (make sure you use the development version. you seem to run both stable and development). Use wget or curl to grab RawTherapee-dev-x86_64-version.txt. Compare and create a message when not the same.
EDIT: About your Nikon Coolpix P950:
If you want/need better support in RawTherapee, or help the community in general, you might want to have a look at @Thanatomanic’s post right here.