[Bugfix]: serialize config by value for --trust-remote-code (#6751)

Signed-off-by: Travis Johnson <tsjohnso@us.ibm.com>
Co-authored-by: Cyrus Leung <cyrus.tl.leung@gmail.com>

vllm/engine/arg_utils.py

@@ -16,6 +16,8 @@ from vllm.config import (CacheConfig, ConfigFormat, DecodingConfig,
 from vllm.executor.executor_base import ExecutorBase
 from vllm.logger import init_logger
 from vllm.model_executor.layers.quantization import QUANTIZATION_METHODS
+from vllm.transformers_utils.config import (
+    maybe_register_config_serialize_by_value)
 from vllm.transformers_utils.utils import check_gguf_file
 from vllm.utils import FlexibleArgumentParser
 
@@ -924,6 +926,8 @@ class EngineArgs:
                     "supported for multimodal models and has been disabled.")
             self.enable_prefix_caching = False
 
+        maybe_register_config_serialize_by_value(self.trust_remote_code)
+
         cache_config = CacheConfig(
             # neuron needs block_size = max_model_len
             block_size=self.block_size if self.device != "neuron" else