chore: prettier source code

src/stepper/index.js

@@ -261,7 +261,7 @@ export default createComponent({
   },
 
   render() {
-    const createListeners = type => ({
+    const createListeners = (type) => ({
       on: {
         click: () => {
           this.type = type;

src/stepper/test/index.spec.js

@@ -172,7 +172,7 @@ test('stepper blur', () => {
     },
   });
 
-  wrapper.vm.$on('input', value => {
+  wrapper.vm.$on('input', (value) => {
     wrapper.setProps({ value });
   });