copy_table.yml in bigquery_migration-0.3.0

- old
+ new

@@ -1,6 +1,6 @@
 bigquery: &bigquery
-  json_keyfile: example/your-project-000.json
+  credentials_file: example/your-project-000.json
   dataset: your_dataset_name
   table: your_table_name
 
 actions:
 - action: create_dataset