Update test to add required field

Author: jamiebenstead

spec/features/admin/schools_spec.rb

@@ -79,7 +79,7 @@
 
     describe 'when the school is in the United States and has a postal code' do
       before do
-        school.update(country_code: 'US', postal_code: '90210', district_nces_id: '010000000001', reference: nil)
+        school.update(country_code: 'US', postal_code: '90210', district_name: 'Some District', district_nces_id: '010000000001', reference: nil)
         get admin_school_path(school)
       end