Add Mistral Small 4 (Pixtral) support (#20708)

Signed-off-by: Xinyuan Tong <xinyuantong.cs@gmail.com>
Co-authored-by: Alex Nails <alexnails@radixark.ai>
Co-authored-by: Dimitrios Bariamis <12195802+dbari@users.noreply.github.com>
Co-authored-by: dbari <dbari@users.noreply.github.com>

python/sglang/srt/configs/jet_nemotron.py

@@ -25,18 +25,18 @@ class JetBlockConfig:
 class JetNemotronConfig(PretrainedConfig):
     model_type: str = "jet_nemotron"
 
-    efficient_attention_config: dict[str, dict[str, Any]]
-    hidden_act: str
-    hidden_size: int
-    initializer_range: float
-    intermediate_size: int
-    layer_types: list[str]
-    max_position_embeddings: int
-    num_attention_heads: int
-    num_key_value_heads: int
-    rms_norm_eps: float
-    rope_scaling: None
-    rope_theta: float
+    efficient_attention_config: dict[str, dict[str, Any]] = None
+    hidden_act: str = None
+    hidden_size: int = None
+    initializer_range: float = None
+    intermediate_size: int = None
+    layer_types: list[str] = None
+    max_position_embeddings: int = None
+    num_attention_heads: int = None
+    num_key_value_heads: int = None
+    rms_norm_eps: float = None
+    rope_scaling: None = None
+    rope_theta: float = None
 
     @property
     def full_attention_layer_ids(self) -> list[int]: