list_subscriptions: Encoded list_subscriptions parameters.

Rectified the list_subscriptions api parameters to ,
take up default parameters rather than a dictionary .

As discussed within zulip/zulip#16698

zulip/zulip/__init__.py

@@ -1278,14 +1278,16 @@ def remove_alert_words(self, alert_words: List[str]) -> Dict[str, Any]:
             }
         )
 
-    def list_subscriptions(self, request: Optional[Dict[str, Any]] = None) -> Dict[str, Any]:
+    def list_subscriptions(self, include_subscribers: bool = False) -> Dict[str, Any]:
         '''
             See examples/list-subscriptions for example usage.
         '''
         return self.call_endpoint(
             url='users/me/subscriptions',
             method='GET',
-            request=request,
+            request={
+                'include_subscribers': include_subscribers
+            }
         )
 
     def add_subscriptions(self, streams: Iterable[Dict[str, Any]], **kwargs: Any) -> Dict[str, Any]: