Revert "Merge branch...
Revert "Merge branch '55-mqtt_user-table-should-have-unique-constraint-on-username-field' into 'main'"
This reverts merge request !112 (merged)
Revert "Merge branch '55-mqtt_user-table-should-have-unique-constraint-on-username-field' into 'main'"
This reverts merge request !112 (merged)