Fix `ROOT / data` when running W&B `log_dataset()` (#6606)

* Fix missing data folder when running log_dataset

* Use ROOT/'data'

* PEP8 whitespace

utils/loggers/wandb/wandb_utils.py

@@ -356,7 +356,7 @@ class WandbLogger():
         # create a _wandb.yaml file with artifacts links if both train and test set are logged
         if not log_val_only:
             path = (path.stem if overwrite_config else path.stem + '_wandb') + '.yaml'  # updated data.yaml path
-            path = Path('data') / path
+            path = ROOT / 'data' / path
             data.pop('download', None)
             data.pop('path', None)
             with open(path, 'w') as f: