fix(pt): use eval mode in the Python interface (#4404)

Same as #4402

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- **New Features**
- Enhanced model initialization by ensuring the model is set to
evaluation mode immediately after loading, improving inference accuracy.
  
- **Bug Fixes**
- Corrected the control flow during model setup to prevent potential
issues during evaluation.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Signed-off-by: Jinzhe Zeng <jinzhe.zeng@rutgers.edu>

Author: njzjz

deepmd/pt/infer/deep_eval.py

@@ -143,6 +143,7 @@ def __init__(
                 self.model_def_script = {}
         else:
             raise ValueError("Unknown model file format!")
+        self.dp.eval()
         self.rcut = self.dp.model["Default"].get_rcut()
         self.type_map = self.dp.model["Default"].get_type_map()
         if isinstance(auto_batch_size, bool):