Enhancement: Update reva to v1.6.1-0.20210223065028-53f39499762e

* quota querying and tree accounting [cs3org/reva#1405](https://github.com/cs3org/reva/pull/1405)

https://github.com/owncloud/ocis/pull/1683
https://github.com/cs3org/reva/pull/1405
