Fix missing banner import

assets/javascripts/wizard/initializers/custom-wizard-step.js.es6

@@ -7,6 +7,7 @@ export default {
     const StepModel = requirejs("wizard/models/step").default;
     const StepComponent = requirejs("wizard/components/wizard-step").default;
     const ajax = requirejs("wizard/lib/ajax").ajax;
+    const getUrl = requirejs("discourse-common/lib/get-url").default;
     const cook = requirejs("discourse/plugins/discourse-custom-wizard/wizard/lib/text-lite").cook;
     
     StepModel.reopen({