Fix the issue of decoding a non-UTF-8 encoded file using UTF-8 (#389)

api/requirements.txt

@@ -30,4 +30,5 @@ jieba==0.42.1
 celery==5.2.7
 redis~=4.5.4
 pypdf==3.8.1
-openpyxl==3.1.2
+openpyxl==3.1.2
+chardet~=5.1.0