set the default encoding to utf-8

jawiki-20220404-c400.py

@@ -49,7 +49,7 @@ class JaWiki20220404Passages(datasets.GeneratorBasedBuilder):
     def _generate_examples(self, filepath: str) -> Tuple[str, Dict[str, Any]]:
         logger.info(f"generating examples from {filepath}")
 
-        with gzip.open(filepath, "rt") as f:
+        with gzip.open(filepath, "rt", encoding="utf-8") as f:
             reader = csv.DictReader(f, delimiter="\t")
             # the tsv file has a header [id, title, text]
             for key, data in enumerate(reader):