Bump es version

We leave async function in here which are newer than ES2015.

Author: sebmarkbage

scripts/rollup/validate/eslintrc.esm.js

@@ -45,7 +45,7 @@ module.exports = {
     jest: true,
   },
   parserOptions: {
-    ecmaVersion: 2015,
+    ecmaVersion: 2017,
     sourceType: 'module',
   },
   rules: {