try to get SQS queue before creating it

In some environments permissions for an IAM role or access key might not include "SQS create".
The broker should first try to get the queue and if this fails try to create it as fall back to the current default behaviour.

django_q/brokers/aws_sqs.py

@@ -1,9 +1,13 @@
 from boto3 import Session
+from botocore.client import ClientError
 
 from django_q.brokers import Broker
 from django_q.conf import Conf
 
 
+QUEUE_DOES_NOT_EXIST = "AWS.SimpleQueueService.NonExistentQueue"
+
+
 class Sqs(Broker):
     def __init__(self, list_key: str = Conf.PREFIX):
         self.sqs = None
@@ -62,4 +66,13 @@ class Sqs(Broker):
 
     def get_queue(self):
         self.sqs = self.connection.resource("sqs")
+
+        try:
+            # try to return an existing queue by name. If the queue does not
+            # exist try to create it.
+            return self.sqs.get_queue_by_name(QueueName=self.list_key)
+        except ClientError as exp:
+            if not exp.response["Error"]["Code"] == QUEUE_DOES_NOT_EXIST:
+                raise exp
+
         return self.sqs.create_queue(QueueName=self.list_key)