add pixtral template

Former-commit-id: e0bcaa6c6e902e29361438a6d215bbc2535b648f

src/llamafactory/data/mm_plugin.py

@@ -323,6 +323,12 @@ class PaliGemmaPlugin(BasePlugin):
         mm_inputs["token_type_ids"] = _get_paligemma_token_type_ids(imglens, seqlens, processor)
         return mm_inputs
 
+class PixtralPlugin(BasePlugin):
+    #TODO preprocess according to Pixtral hf
+    from transformers import LlavaForConditionalGeneration
+    @override
+    def _preprocess_image(self, image: "ImageObject", **kwargs) -> "ImageObject":
+        pass
 
 class Qwen2vlPlugin(BasePlugin):
     @override

src/llamafactory/data/template.py

@@ -821,6 +821,13 @@ _register_template(
     replace_eos=True,
 )
 
+_register_template(
+    name="pixtral",
+    format_user=StringFormatter(slots=["[INST] {{content}} [/INST]"]),
+    format_prefix=EmptyFormatter(slots=[{"bos_token"}]),
+    mm_plugin=get_mm_plugin(name="pixtral", image_token="[IMG]")
+)
+
 
 _register_template(
     name="qwen",