Log Message:
php-nextcloud: Update to 21.0.0

Changelog:
Version 21.0.0 February 22 2021

Changes

The biggest improvements we introduce with Nextcloud 21 are:

  * High Performance Back-end for Nextcloud Files: reduces server load from
    desktop clients and web interface polling by 90% while delivering instant
    notifications to users.
  * And a wide range of performance improvements all over on top, decreasing
    loading times of pages and reducing load on the server
  * Collaborative features: new Whiteboard, author colours in Text and
    Document Templates to increase team productivity
  * Nextcloud Talk: debuts message status indicators, a raise hand feature, a
    group conversation description and more!
  * A range of Groupware improvements like drag'n'drop and nicer threading in
    Mail and syncing social media avatars in Contacts.