php-nextcloud: Update to 20.0.0

Changelog:
20.0.0

The three biggest features we introduce with Nextcloud 20 are:

    Our new dashboard provides a great starting point for the day with over a dozen widgets ranging from Twitter and Github to Moodle and Zammad already available
    Search was unified, bringing search results of Nextcloud apps as well as external services like Gitlab, Jira and Discourse in one place
    Talk introduced bridging to other platforms including MS Teams, Slack, IRC, Matrix and a dozen others

Some other improvements we want to highlight include:

    Notifications and Activities were brought together, making sure you won't miss anything important
    We added a 'status' setting so you can communicate to other users what you are up to
    Talk also brings dashboard and search integration, emoji picker, upload view, camera and microphone settings, mute and more
    Calendar integrates in dashboard and search, introduced a list view and design improvements
    Mail introduces threaded view, mailbox management and more
    Deck integrates with dashboard and search, introduces Calendar integration, modal view for card editing and series of smaller improvements
    Flow adds push notification and webhooks so other web apps can easily integrate with Nextcloud
    Text introduced direct linking to files in Nextcloud
    Files lets you add a description to public link shares

(ryoon)