Set ecmaVersion to 2018

sindresorhus · sindresorhus · commit 09d190ebfb0d · 2018-02-11T14:00:22.000+07:00
This only sets what ESLint can parse.
diff --git a/index.js b/index.js
@@ -10,7 +10,7 @@ module.exports = {
 				es6: true
 			},
 			parserOptions: {
-				ecmaVersion: 2017,
+				ecmaVersion: 2018,
 				sourceType: 'module'
 			},
 			rules: {
