Increase the minimum lenght of a users name from 0 to 1

Author: drGrove

schema/sql/schema.sql

@@ -19,7 +19,7 @@ create table "hosts" (
 create sequence user_id minvalue 4000 maxvalue 59999 no cycle;
 
 create domain username_t text check (
-  value ~ '^[a-z][a-z0-9]{0,30}$'
+  value ~ '^[a-z][a-z0-9]{4,30}$'
 );
 
 create table "passwd" (