fixed type in version controller

celery/backends/mongodb.py

@@ -80,7 +80,7 @@ class MongoBackend(BaseBackend):
 
 
         # default options according to pymongo version
-        if pymongo.version_tuple >= 3:
+        if pymongo.version_tuple >= (3,):
             self.options.setdefault('maxPoolSize', self.max_pool_size)
         else:
             self.options.setdefault('max_pool_size', self.max_pool_size)