git_deploy: fix initialization regression

New repos have not yet saved the valid state, so it is necessary to
provide a default value when attempting to access the "is_valid"
field.

Signed-off-by:  Eric Callahan <arksine.code@gmail.com>

moonraker/components/update_manager/git_deploy.py

@@ -48,7 +48,7 @@ class GitDeploy(AppDeploy):
     async def initialize(self) -> Dict[str, Any]:
         storage = await super().initialize()
         await self.repo.restore_state(storage)
-        self._is_valid = storage["is_valid"]
+        self._is_valid = storage.get("is_valid", self.repo.is_valid())
         if not self.needs_refresh():
             self.repo.log_repo_info()
         return storage