chore: Align dependencies (and PHP version) with current lowest supported Nextcloud version

[susnux]

• Target version: main

Summary

The lowest supported version is Nextcloud 24, so we can update the dependencies like nextcloud/ocp and PHP to 7.4.

Checklist

• [x] Code is properly formatted
• [x] Sign-off message is added to all commits
• [x] Documentation (manuals or wiki) has been updated or is not required