SOLVED OpenProject version 10
After some longer time, we finally managed to update OpenProject to version 10. This took quite long, since the Cloudron package was using mysql instead of postgres. Unfortunately OpenProject removed support for mysql in that version, so we had to create a database migration script. The new version is published as a major package version upgrade, which means it will not be applied automatically, but has to be done manually from the dashboard.
Please make sure to have backups for the app in case the database migration does not work out for you and if so, please report here.
Just a heads up, OpenProject already published version 10.2.1 while our updated package is only on 10.0.2 for now. It will be updated shortly once that database migration update went well.