cubicweb-timesheet #3157250 limit done_by and todo_by to activate users [validation pending]

prioritynormal
typeenhancement
done in0.9.0
load0.100
load left0.000
closed by#3bd40f98a38b [schema] limit done_by and todo_by to activate users (closes #3157250)
patch[schema] limit done_by and todo_by to activate users (closes #3157250) [applied]