only test on newest dev transformers

tests/models/test_initialization.py

@@ -1,6 +1,7 @@
 from unittest.mock import patch
 
 import pytest
+import transformers
 from transformers import PretrainedConfig
 
 from vllm import LLM
@@ -11,6 +12,9 @@
 @pytest.mark.parametrize("model_arch", HF_EXAMPLE_MODELS.get_supported_archs())
 def test_can_initialize(model_arch):
     model_info = HF_EXAMPLE_MODELS.get_hf_info(model_arch)
+    if (model_arch == "Cohere2ForCausalLM"
+            and transformers.__version__ < "4.48.0"):
+        pytest.skip(reason="Model introduced in HF >= 4.48.0")
     if not model_info.is_available_online:
         pytest.skip("Model is not available online")