Fix eslint issues

.eslintrc

@@ -5,7 +5,7 @@ env:
   es6: true
 
 parserOptions:
-  ecmaVersion: 2016
+  ecmaVersion: 2017
 
 rules:
   # Possible Errors

CONTRIBUTING.md

@@ -179,4 +179,3 @@ A simple bug fix:
 ```
 fix: Handle multi-byte characters in search logic
 ```
-

test/cli/invalid-args.test.js

@@ -28,7 +28,7 @@ test('launch w/ invalid host:port', (t) => {
 });
 
 test('launch w/ unavailable port', async (t) => {
-  const blocker = createServer(socket => socket.end());
+  const blocker = createServer((socket) => socket.end());
   const port = await new Promise((resolve, reject) => {
     blocker.on('error', reject);
     blocker.listen(0, '127.0.0.1', () => resolve(blocker.address().port));