Feature/nat 410 add validator for tty number

gso/workflows/iptrunk/migrate_iptrunk.py

@@ -76,7 +76,6 @@ def initial_input_form_generator(subscription_id: UUIDstr) -> FormGenerator:
         def validate_tt_number(cls, tt_number: str) -> str:
             return validate_tt_number(tt_number)
 
-
     migrate_form_input = yield IPTrunkMigrateForm
 
     current_routers = [