Fix condition check for league baselines in hitter tab of Streamlit app

- Updated the condition to check if the selected table variable is in the list of league baseline options, ensuring correct functionality for data loading.
- This change improves the accuracy of the loading spinner display when accessing league aggregate data.

src/streamlit_app.py

@@ -245,7 +245,7 @@ with hitter_tab:
     hitter_disp_container = hitter_disp_container.empty()
 
     with hitter_disp_container:
-        if table_var_hitter.isin(['League Aggregate Baselines', 'League Short Term Baselines', 'League Long Term Baselines']):
+        if table_var_hitter in (['League Aggregate Baselines', 'League Short Term Baselines', 'League Long Term Baselines']):
             with st.spinner("Full league baselines can take some time to load", show_time=True):
                 time.sleep(5)
         st.dataframe(st.session_state['hitter_disp_frame'].style.background_gradient(axis=0).background_gradient(cmap='RdYlGn').format(precision=2), height = 750, use_container_width = True, hide_index = True)