Add coverage for model normalizations (#31734)

spec/models/webhook_spec.rb

@@ -29,10 +29,8 @@ RSpec.describe Webhook do
   end
 
   describe 'Normalizations' do
-    it 'cleans up events values' do
-      record = described_class.new(events: ['account.approved', 'account.created     ', ''])
-
-      expect(record.events).to eq(%w(account.approved account.created))
+    describe 'events' do
+      it { is_expected.to normalize(:events).from(['account.approved', 'account.created     ', '']).to(%w(account.approved account.created)) }
     end
   end