Fix eslint line length warning

Author: marco-c

src/vapid-helper.js

@@ -80,7 +80,8 @@ function validateSubject(subject) {
     if (!subjectParseResult.hostname) {
       throw new Error('Vapid subject is not a url or mailto url. ' + subject);
     } else if (subjectParseResult.hostname === 'localhost' && subjectParseResult.protocol === 'https:') {
-      console.warn('VAPID subject points to a localhost web URI, which is unsupported by Apple\'s push notification server and will result in a BadJwtToken error when sending notifications.');
+      console.warn('VAPID subject points to a localhost web URI, which is unsupported by Apple\'s push notification '
+      + 'server and will result in a BadJwtToken error when sending notifications.');
     }
   }
 }