validate alphanumeric values

src/layouts/payment-method/promo-modal-question/promo-question/promo-question.vue

@@ -8,6 +8,7 @@
         cornerStyle="rounded"
         :displayQuestionText="false"
         isRequired
+        @input="validateAlphanumeric"
         validationRules="promo-required" />
 </template>
 
@@ -38,6 +39,11 @@ export default {
             },
         },
     },
+    methods: {
+        validateAlphanumeric() {
+            this.value = this.value.replace(/[^a-zA-Z0-9]/g, "");
+        },
+    },
     components: {
         textboxQuestion,
     },