fix mistake and improve typing

just noticed i made a logic mistake at line 45, this commit is fixing that

Author: umbertov

src/nn_core/callbacks.py

@@ -17,7 +17,7 @@ class NNTemplateCore(Callback):
     def __init__(self, restore_cfg: Optional[DictConfig]):
         self.resume_ckpt_path, self.resume_run_version = parse_restore(restore_cfg)
         self.restore_mode: Optional[str] = restore_cfg.get("mode", None) if restore_cfg is not None else None
-        self.restore_strict: Optional[bool] = restore_cfg.get("strict", None) if restore_cfg is not None else None
+        self.restore_strict: bool = restore_cfg.get("strict", True) if restore_cfg is not None else True
 
     @property
     def resume_id(self) -> Optional[str]:
@@ -42,7 +42,7 @@ def setup(self, trainer: "pl.Trainer", pl_module: "pl.LightningModule", stage: O
         if self.restore_mode == "finetune":
             checkpoint = NNCheckpointIO.load(path=Path(self.resume_ckpt_path))
 
-            pl_module.load_state_dict(checkpoint["state_dict"], strict=self.restore_strict or True)
+            pl_module.load_state_dict(checkpoint["state_dict"], strict=self.restore_strict)
 
     def on_train_end(self, trainer: pl.Trainer, pl_module: pl.LightningModule) -> None:
         if self._is_nnlogger(trainer):