Fix bug in UserDatatable query affecting PostgreSQL
Fix bug in UserDatatable query affecting PostgreSQL

Resolves:

    $ docker-compose run --rm osem bundle exec rspec ./spec/datatables/user_datatable_spec.rb:97
    …
    ActiveRecord::StatementInvalid:
    PG::GroupingError: ERROR:  column "users.id" must appear in the GROUP BY clause or be used in an aggregate function

AndrewKvalheim/osem,AndrewKvalheim/osem,SeaGL/osem,openSUSE/osem,SeaGL/osem,differentreality/osem,hennevogel/osem,AndrewKvalheim/osem,hennevogel/osem,hennevogel/osem,differentreality/osem,openSUSE/osem,differentreality/osem,differentreality/osem,SeaGL/osem,hennevogel/osem,openSUSE/osem