treat do_lower_case in the same way as the sentence-transformers library (#11815)

Signed-off-by: Max de Bayser <mbayser@br.ibm.com>

tests/entrypoints/openai/test_serving_chat.py

@@ -35,6 +35,7 @@ class MockModelConfig:
     logits_processor_pattern = None
     diff_sampling_param: Optional[dict] = None
     allowed_local_media_path: str = ""
+    encoder_config = None
 
     def get_diff_sampling_param(self):
         return self.diff_sampling_param or {}