fix the weights loading for the apertus model

Author: nathanrchn

vllm/model_executor/models/apertus.py

@@ -415,6 +415,11 @@ def load_weights(self, weights: Iterable[tuple[str,
             (".qkv_proj", ".v_proj", "v"),
         ]
         params_dict = dict(self.named_parameters())
+
+        # we need to load the buffers for beta and eps (XIELU)
+        for name, buffer in self.named_buffers():
+            params_dict[name] = buffer
+
         loaded_params: set[str] = set()
         for name, loaded_weight in weights:
             if "rotary_emb.inv_freq" in name: