Update app.py

app.py

@@ -30,7 +30,7 @@ def generate_code(source, destination, chunking_strategy, chunk_size, chunk_over
         chunking_config = f'''
         chunker_config=ChunkerConfig(
             chunking_strategy="{chunking_strategy}",
-            chunk_size={chunk_size if chunk_size is not None else 1000},
+            chunk_max_characters={chunk_size if chunk_size is not None else 1000},
             chunk_overlap={chunk_overlap if chunk_overlap is not None else 20}
         ),'''