Fix position filter in app.py from "D" to "DST" for flex player selection, ensuring correct scoring logic in GPP contests.

app.py

@@ -515,7 +515,7 @@ with tab1:
                                         total_score += pulp.lpSum([player_vars[idx] for idx in sub_idx]) == 1
                                     
                                     for flex in flex_file['Position'].unique():
-                                        sub_idx = flex_file[flex_file['Position'] == "D"].index
+                                        sub_idx = flex_file[flex_file['Position'] == "DST"].index
                                         total_score += pulp.lpSum([player_vars[idx] for idx in sub_idx]) == 1
         
                                 player_count = []
@@ -973,7 +973,7 @@ with tab1:
                                         total_score += pulp.lpSum([player_vars[idx] for idx in sub_idx]) == 1
                                     
                                     for flex in flex_file['Position'].unique():
-                                        sub_idx = flex_file[flex_file['Position'] == "D"].index
+                                        sub_idx = flex_file[flex_file['Position'] == "DST"].index
                                         total_score += pulp.lpSum([player_vars[idx] for idx in sub_idx]) == 1
         
                                 player_count = []