fix(picker): recover emit (#3755)

fix #3749

packages/picker/index.ts

@@ -53,6 +53,21 @@ VantComponent({
       return Promise.all(stack);
     },
 
+    emit(event: WechatMiniprogram.TouchEvent) {
+      const { type } = event.currentTarget.dataset;
+      if (this.simple) {
+        this.$emit(type, {
+          value: this.getColumnValue(0),
+          index: this.getColumnIndex(0),
+        });
+      } else {
+        this.$emit(type, {
+          value: this.getValues(),
+          index: this.getIndexes(),
+        });
+      }
+    },
+
     onChange(event: WechatMiniprogram.CustomEvent) {
       if (this.simple) {
         this.$emit('change', {