remove bluebird dependency

package.json

@@ -37,7 +37,6 @@
     "sinon": "~1.17.3"
   },
   "dependencies": {
-    "bluebird": "~3.3.5",
     "debug": "~2.2.0",
     "elasticsearch": "~11.0.1",
     "error": "~7.0.2",

src/worker.js

@@ -1,7 +1,6 @@
 import events from 'events';
 import Puid from 'puid';
 import moment from 'moment';
-import Bluebird from 'bluebird';
 import logger from './helpers/logger';
 import { jobStatuses } from './helpers/constants';
 import { WorkerTimeoutError } from './helpers/errors';