Enhancement: Update ownCloud Web to v5.3.0

Tags: web

We updated ownCloud Web to v5.3.0. Please refer to the changelog (linked) for details on the web release.

https://github.com/owncloud/web/pull/6561
https://github.com/owncloud/ocis/pull/3291
https://github.com/owncloud/ocis/pull/3375
https://github.com/owncloud/web/releases/tag/v5.3.0
