Rename model name

Author: juliendenize

convert_hf_to_gguf.py

@@ -7683,7 +7683,7 @@ def modify_tensors(self, data_torch: Tensor, name: str, bid: int | None) -> Iter
 
 
 class MistralModel(TextModel):
-    model_name = "mistral"
+    model_name = "Mistral"
     model_arch = MODEL_ARCH.LLAMA
     undo_permute = True
 
@@ -7748,7 +7748,7 @@ def modify_tensors(
 
 
 class PixtralModel(MmprojModel):
-    model_name = "mistral"
+    model_name = "Pixtral"
     img_break_tok_id = -1
 
     def __init__(self, *args, **kwargs):