remove metadata conversion

Author: aryanA101a

libzim/libzim.pyx

@@ -576,10 +576,6 @@ class Creator(_Creator):
         self, name: str, content: Union[str, bytes, datetime.date, datetime.datetime],
         mimetype: str = "text/plain;charset=UTF-8"
     ):
-        if name == "Date" and isinstance(content, (datetime.date, datetime.datetime)):
-            content = content.strftime("%Y-%m-%d").encode("UTF-8")
-        if isinstance(content, str):
-            content = content.encode("UTF-8")
         super().add_metadata(name=name, content=content, mimetype=mimetype)
 
     def __repr__(self) -> str: