tweak m2m model code

app.py

@@ -180,7 +180,10 @@ def m2m_trans(article, target_language):
     result_lang = detect_lang(article)
 
     if result_lang != target_language:
-        return m2m_model.translate(article)
+        if target_language == "English":
+            return m2m_model.translate(article, target_lang="en")
+        elif target_language == "Chinese":
+            return m2m_model.translate(article, target_lang="zh")
     else:
         return "Error: You chose the same language as the article detected language. Please reselect language and try again."