remove ResourcesT.cached_timestamp()

Signed-off-by: flashdagger <flashdagger@googlemail.com>

zammadoo/resource.py

@@ -61,8 +61,8 @@ def reload(self, expand=False) -> None:
         info.update(new_info)
 
     def last_request_at(self) -> Optional[datetime]:
-        """:return: the last request timestamp as :class:`datetime` or ``None``"""
-        return self.parent.cached_timestamp(self.id)
+        """:return: the last request timestamp"""
+        return self.parent.cache.timestamp(self.url)
 
 
 class UserProperty:

zammadoo/resources.py

@@ -3,7 +3,6 @@
 
 import weakref
 from dataclasses import asdict
-from datetime import datetime
 from functools import partial
 from typing import (
     TYPE_CHECKING,
@@ -88,9 +87,6 @@ def cached_info(self, rid: int, refresh=True, expand=False) -> "JsonDict":
 
         return cache.setdefault_by_callback(item, callback)
 
-    def cached_timestamp(self, rid: int) -> Optional[datetime]:
-        return self.cache.timestamp(f"{self.url}/{rid}")
-
     def delete(self, rid: int) -> None:
         """:meta private:"""
         item = f"{self.url}/{rid}"