fix: rename op_offloat to op_offload in llama.py

[sergey21000]

Fix typo in variable name: replace op_offloat with op_offload in llama.py (v0.3.14), that caused AttributeError during model copying

Steps to Reproduce:

# pip install llama_cpp_python 
from copy import copy, deepcopy
from llama_cpp import Llama

model = Llama.from_pretrained(
    repo_id='bartowski/google_gemma-3-1b-it-GGUF',
    filename='google_gemma-3-1b-it-Q8_0.gguf',
    verbose=False,
)
deepcopy(model)

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
[/tmp/ipython-input-119572725.py](https://localhost:8080/#) in <cell line: 0>()
      8     verbose=False,
      9 )
---> 10 deepcopy(model)

1 frames
[/usr/lib/python3.11/copy.py](https://localhost:8080/#) in deepcopy(x, memo, _nil)
    159                     reductor = getattr(x, "__reduce_ex__", None)
    160                     if reductor is not None:
--> 161                         rv = reductor(4)
    162                     else:
    163                         reductor = getattr(x, "__reduce__", None)

[/usr/local/lib/python3.11/dist-packages/llama_cpp/llama.py](https://localhost:8080/#) in __getstate__(self)
   2098             offload_kqv=self.context_params.offload_kqv,
   2099             flash_attn=self.context_params.flash_attn,
-> 2100             op_offloat=self.context_params.op_offloat,
   2101             swa_full=self.context_params.swa_full,
   2102             # Sampling Params

AttributeError: 'llama_context_params' object has no attribute 'op_offloat'

Impact: breaks Gradio integration

# pip install gradio 
import gradio as gr
model_state = gr.State({'model': model})
# AttributeError: 'llama_context_params' object has no attribute 'op_offloat'