Server.panes: Fix listing of panes

Would list only panes in attached session, rather than all in a server.

Author: tony

src/libtmux/server.py

@@ -542,7 +542,7 @@ def panes(self) -> QueryList[Pane]:
             Pane(server=self, **obj)
             for obj in fetch_objs(
                 list_cmd="list-panes",
-                list_extra_args=["-s"],
+                list_extra_args=("-a",),
                 server=self,
             )
         ]