Fix saving of saves from other machines.

Need to reset the persisted save paths on load, since the file that was
loaded may have been moved since it was saved and the original location
may no longer be accessible.

Fixes https://github.com/dcs-liberation/dcs_liberation/issues/2756.

tests/persistence/conftest.py

@@ -4,11 +4,13 @@ from typing import cast
 import pytest
 
 from game import Game
+from game.persistence import SaveManager
 
 
 class StubGame:
     def __init__(self) -> None:
         self.date = datetime.date.min
+        self.save_manager = SaveManager(cast(Game, self))
 
 
 @pytest.fixture