Fix issue unselecting date

src/streamlit_app.py

@@ -51,7 +51,7 @@ for key, value in defaults.items():
 
 # Sidebar filters
 with st.sidebar:
-    st.session_state.date = st.date_input("Date", st.session_state.date)
+    st.session_state.date = st.date_input("Date", value=None)
     st.session_state.symbols = st.multiselect(
         "Symbols", load_symbols(), st.session_state.symbols
     )