Reorder split names

Reorder split names in the YAML metadata to be aligned with the order in the loading script.
See: https://github.com/huggingface/datasets/issues/5258

README.md

@@ -30,15 +30,15 @@ dataset_info:
   - name: target
     dtype: string
   splits:
-  - name: test
-    num_bytes: 77530
-    num_examples: 1497
   - name: train
     num_bytes: 6724250
     num_examples: 67389
   - name: validation
     num_bytes: 408752
     num_examples: 4018
+  - name: test
+    num_bytes: 77530
+    num_examples: 1497
   download_size: 1845699
   dataset_size: 7210532
 ---