make sure lr is not a tensor
Author: winglian
Pull request: yes

# What does this PR do?
There seems to be a slight regression where using deepspeed is completely broken and saving checkpoints will fail during the trainer state save step because the LR is still a tensor. This is probably also the root cause that also would fix #37704. The is Tensor check is used in the `else` part of the conditional, but not the `if` clause.

This PR makes sure when we grab the learning rate while using deepspeed that it isn't a Tensor type.

Saving the trainer state fails with:

```
[rank0]:   File "/workspace/axolotl/src/axolotl/train.py", line 215, in execute_training
[rank0]:     trainer.train(resume_from_checkpoint=resume_from_checkpoint)
[rank0]:   File "/root/miniconda3/envs/py3.11/lib/python3.11/site-packages/transformers/trainer.py", line 2245, in train
[rank0]:     return inner_training_loop(
[rank0]:            ^^^^^^^^^^^^^^^^^^^^
[rank0]:   File "/root/miniconda3/envs/py3.11/lib/python3.11/site-packages/transformers/trainer.py", line 2661, in _inner_training_loop
[rank0]:     self._maybe_log_save_evaluate(
[rank0]:   File "/root/miniconda3/envs/py3.11/lib/python3.11/site-packages/transformers/trainer.py", line 3103, in _maybe_log_save_evaluate
[rank0]:     self._save_checkpoint(model, trial)
[rank0]:   File "/workspace/axolotl/src/axolotl/core/trainers/base.py", line 612, in _save_checkpoint
[rank0]:     return super()._save_checkpoint(model, trial, **kwargs)
[rank0]:            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[rank0]:   File "/root/miniconda3/envs/py3.11/lib/python3.11/site-packages/transformers/trainer.py", line 3228, in _save_checkpoint
[rank0]:     self.state.save_to_json(os.path.join(output_dir, TRAINER_STATE_NAME))
[rank0]:   File "/root/miniconda3/envs/py3.11/lib/python3.11/site-packages/transformers/trainer_callback.py", line 146, in save_to_json
[rank0]:     json_string = json.dumps(dataclasses.asdict(self), indent=2, sort_keys=True) + "\n"
[rank0]:                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[rank0]:   File "/root/miniconda3/envs/py3.11/lib/python3.11/json/__init__.py", line 238, in dumps
[rank0]:     **kw).encode(obj)
[rank0]:           ^^^^^^^^^^^
[rank0]:   File "/root/miniconda3/envs/py3.11/lib/python3.11/json/encoder.py", line 202, in encode
[rank0]:     chunks = list(chunks)
[rank0]:              ^^^^^^^^^^^^
[rank0]:   File "/root/miniconda3/envs/py3.11/lib/python3.11/json/encoder.py", line 432, in _iterencode
[rank0]:     yield from _iterencode_dict(o, _current_indent_level)
[rank0]:   File "/root/miniconda3/envs/py3.11/lib/python3.11/json/encoder.py", line 406, in _iterencode_dict
[rank0]:     yield from chunks
[rank0]:   File "/root/miniconda3/envs/py3.11/lib/python3.11/json/encoder.py", line 326, in _iterencode_list
[rank0]:     yield from chunks
[rank0]:   File "/root/miniconda3/envs/py3.11/lib/python3.11/json/encoder.py", line 406, in _iterencode_dict
[rank0]:     yield from chunks
[rank0]:   File "/root/miniconda3/envs/py3.11/lib/python3.11/json/encoder.py", line 439, in _iterencode
[rank0]:     o = _default(o)
[rank0]:         ^^^^^^^^^^^
[rank0]:   File "/root/miniconda3/envs/py3.11/lib/python3.11/json/encoder.py", line 180, in default
[rank0]:     raise TypeError(f'Object of type {o.__class__.__name__} '
[rank0]: TypeError: Object of type Tensor is not JSON serializable
```
Here's the deepspeed zero-3 config I'm using, but likely not relevant: https://wandb.ai/axolotl-ai/qwen3-distributed/runs/mg3kc9wv/files/tmp/deepspeed_config_d31f2b33.json


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