Make md5 calculate async

Author: Wh1isper

jupyter_server/services/contents/fileio.py

@@ -478,5 +478,5 @@ async def _save_file(self, os_path, content, format):
     async def _get_md5(self, os_path):
         c, _ = await self._read_file(os_path, "byte")
         md5 = hashlib.md5()  # noqa: S324
-        md5.update(c)
+        await run_sync(md5.update, c)
         return md5.hexdigest()