Enhancement: Update reva to v1.7.1-0.20210531093513-b74a2b156af6 

This reva update includes:
* [fix move in the owncloud storage driver](https://github.com/cs3org/reva/pull/1696)
* [add checksum header to the tus preflight response](https://github.com/cs3org/reva/pull/1702)
* [Add reliability calculations support to Mentix](https://github.com/cs3org/reva/pull/1649)
* [fix response format when accepting shares](https://github.com/cs3org/reva/pull/1724)
* [Datatx createtransfershare](https://github.com/cs3org/reva/pull/1725)

https://github.com/owncloud/ocis/pull/2104
https://github.com/owncloud/ocis/issues/2102
