leaderboard: fix layout

leaderboard.py

@@ -23,7 +23,9 @@ def create_leaderboard_tab():
             row_count=0,
             col_count=0,
         )
+    with gr.Row():
         legend = gr.Markdown(value="")
+
     def update_datasets(system_type: str):
         # When system type changes, clear dataset and table
         dataset_choices = get_datasets(system_type) if system_type else []