Update to the latest pre-realease with the helper

[M5oul]

I usually move the release to "latest", then run the helper.
I can do that because I have permissions on the upstream repository.
But, for people who don't, that would be great if the script could look for the latest unstable release. An option allowing to choose between the stable and the unstable would be nice!

Considering adapting the helper to get the latest pre-release.
We can get the latest pre-release from https://api.github.com/repos/duniter/cesium/releases, but that doesn't looks convenient to filter in.
It seems there is no other way than filtering among all the releases, considering the API about releases.

[yalh76]

There is an auto-updater now , at https://github.com/YunoHost/example_ynh/blob/master/.github/workflows/updater.sh

[M5oul]

Doesn’t work fully, it took the sha256 file, not the zip. I had to force push:
https://github.com/YunoHost-Apps/cesium_ynh/compare/6c9773e8156a2dc653ac1d2527f82e9487c2c646..583fc2da684b27e924105b0fe4b6a0d2c224a7bd