incorrect error message when setting citus.distributed_deadlock_detection_factor

```sql
alter system set citus.distributed_deadlock_detection_factor = 1;
WARNING: citus.distributed_deadlock_detection_factor cannot be less than 1. To disable distributed deadlock detection set the value to -1.
ERROR: invalid value for parameter "citus.distributed_deadlock_detection_factor": 1
```

I was clearly not setting it to a value less than 1. Setting it to 1.000001 works.