Bump OpenJDK to v17 as required by latest Gradle version
Summary
Gradle version bump in 921d0ee8 (probably) is incompatible with Java 11.
Fix Gitlab CI by increasing Java version, as required by latest Gradle version.
Test Plan
Before:
Gitlab CI does not work, complaining about Java version. See for example: https://invent.kde.org/network/kdeconnect-android/-/jobs/950701
After:
Gitlab CI does work