Fix worker error in macOS (getredash#6224)

* Update worker.py
* fix
---------

Co-authored-by: rajat goyal <gyl.rajat@gmail.com>

redash/tasks/worker.py

@@ -1,6 +1,7 @@
 import errno
 import os
 import signal
+import sys
 
 from rq import Queue as BaseQueue
 from rq.job import Job as BaseJob
@@ -10,9 +11,16 @@
 from rq.worker import (
     HerokuWorker,  # HerokuWorker implements graceful shutdown on SIGTERM
 )
+from rq.worker import Worker
 
 from redash import statsd_client
 
+# HerokuWorker does not work in OSX https://github.com/getredash/redash/issues/5413
+if sys.platform == "darwin":
+    BaseWorker = Worker
+else:
+    BaseWorker = HerokuWorker
+
 
 class CancellableJob(BaseJob):
     def cancel(self, pipeline=None):
@@ -45,7 +53,7 @@ class RedashQueue(StatsdRecordingQueue, CancellableQueue):
     pass
 
 
-class StatsdRecordingWorker(HerokuWorker):
+class StatsdRecordingWorker(BaseWorker):
     """
     RQ Worker Mixin that overrides `execute_job` to increment/modify metrics via Statsd
     """
@@ -63,7 +71,7 @@ def execute_job(self, job, queue):
                 statsd_client.incr("rq.jobs.failed.{}".format(queue.name))
 
 
-class HardLimitingWorker(HerokuWorker):
+class HardLimitingWorker(BaseWorker):
     """
     RQ's work horses enforce time limits by setting a timed alarm and stopping jobs
     when they reach their time limits. However, the work horse may be entirely blocked