Fix error with French langage

Got `UnicodeDecodeError: 'charmap' codec can't decode byte 0x9d in position 3265: character maps to <undefined>` when downloading the French split.

mqa.py

@@ -139,7 +139,7 @@ class MQA(datasets.GeneratorBasedBuilder):
             return e[key]
 
         for filename in filenames:
-            with open(filename, "r") as f:
+            with open(filename, "r", encoding="utf-8") as f:
                 domain = []
                 previous_domain = ''
                 for line in f: