Remove unnecessary create call in tag rule model specs

spec/models/tag_rule_spec.rb

@@ -1,11 +1,9 @@
 require 'spec_helper'
 
 describe TagRule, type: :model do
-  let!(:tag_rule) { create(:tag_rule) }
-
   describe "validations" do
     it "requires a enterprise" do
-      expect(tag_rule).to validate_presence_of :enterprise
+      expect(subject).to validate_presence_of(:enterprise)
     end
   end
 end