Updating the write_csv_row function to use the item_id instead of ite…

…m key as changed in the synthetic dataset classes in PR #286

src/gluonts/dataset/artificial/generate_synthetic.py

@@ -56,7 +56,7 @@ def write_csv_row(
  if freq_week_start == "W":
  freq_week_start = f"W-{week_dict[timestamp.weekday()]}"
  timestamp = pd.Timestamp(data["start"], freq=freq_week_start)
- item_id = int(data["item"])
+ item_id = int(data["item_id"])
  for j, target in enumerate(data["target"]):
  # Using convention that there are no missing values before the start date
  if is_missing and j != 0 and j % num_missing == 0: