Update data/metadata.csv

data/metadata.csv

@@ -1,4 +1,4 @@
-filename,question,answer
+file_name,question,answer
 input_image1.png,What is the position of the tennis players on the field?,First tennis player is standing at the baseline. Second player is standing at the baseline.
 input_image2.png,What is the position of the tennis players on the field?,The first and the second tennis player are standing at the baseline of the field.
 input_image3.png,What is the position of the tennis players on the field?,The first tennis player is standing on the baseline of the court. The second player also.