suppresses KeyError when removing key from observable dict mapping

This error is thrown in some test cases when some object gets deleted
but it's not within the dict mapping for some reason.

src/pydase/observer_pattern/observable/observable_object.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+import contextlib
 import logging
 import weakref
 from abc import ABC, abstractmethod
@@ -252,7 +253,8 @@ class _ObservableDict(ObservableObject, dict[str, Any]):
             self.__setitem__(key, self._initialise_new_objects(f'["{key}"]', value))
 
     def __del__(self) -> None:
-        self._dict_mapping.pop(id(self._original_dict))
+        with contextlib.suppress(KeyError):
+            self._dict_mapping.pop(id(self._original_dict))
 
     def __setitem__(self, key: str, value: Any) -> None:
         if not isinstance(key, str):