Convert player columns to string type in app.py

- Added a loop to convert all player columns in the session state 'Contest' dataframe to string type, ensuring consistent data formatting for further processing.
- This change enhances data handling and prevents potential type-related issues during analysis.

app.py

@@ -86,6 +86,8 @@ with tab2:
         col1, col2 = st.columns([1, 8])
         excluded_cols = ['BaseName', 'EntryCount']
         player_columns = [col for col in st.session_state['Contest'].columns if col not in excluded_cols]
+        for col in player_columns:
+            st.session_state['Contest'][col] = st.session_state['Contest'][col].astype(str)
         
         # Create mapping dictionaries
         map_dict = {