This App is used to make actions in github action (like for v18 autotag and autoassign)
Setup is done from the Dolibarr organization - Settings - Github apps.
https://github.com/organizations/Dolibarr/settings/apps/github-apps-for-v18-github-actions

The App ID is saved into organization variables PR18_APP_ID and the App Client Secret into PR18_SECRET_KEY, into section "Actions secrets and variables".

They are used by some github workflow files.