Fix typo in fnl_monthly_customer_count

Author: joshuadias2212

jaffle_shop/models/final/sales/_models.yml

@@ -1,7 +1,7 @@
 version: 2
 
 models:
-  name: fnl_monthly_customer_count
+- name: fnl_monthly_customer_count
   meta:
     owner: kensuke.morris@octoenergy.com
   description: | 
@@ -11,5 +11,4 @@ models:
       description: Primary key
       tests:
         - unique
-        - not_null
-
+        - not_null