Feature/nat 410 add validator for tty number

gso/workflows/iptrunk/create_iptrunk.py

@@ -59,7 +59,7 @@ def initial_input_form_generator(product_name: str) -> FormGenerator:
         iptrunk_minimum_links: int
 
         @validator("tt_number", allow_reuse=True)
-        def validate_tt_number(cls, tt_number) -> str:
+        def validate_tt_number(cls, tt_number: str) -> str:
             return validate_tt_number(tt_number)
 
     initial_user_input = yield CreateIptrunkForm