Update app.py

app.py

@@ -33,7 +33,7 @@ def generate(prompt):
     pgn_str = StringIO(pgn)
     game = chess.pgn.read_game(pgn_str)
     img = chess.svg.board(game.board())
-    filename = f'moves-{pgn}'
+    filename = f'moves-{pgn}.svg'
     with open(filename, 'w') as f:
         f.write(img)
     return pgn, filename