fix: allow empty string to search product route

packages/medusa/src/api/routes/store/products/search.js

@@ -4,7 +4,9 @@ import ProductService from "../../../../services/product"
 export default async (req, res) => {
   const schema = Validator.object()
     .keys({
-      q: Validator.string().required(),
+      q: Validator.string()
+        .required()
+        .allow(""),
       offset: Validator.number().optional(),
       limit: Validator.number().optional(),
       filter: Validator.any(),