community[patch]: BedrockChat -> Support Titan express as chat model (#15408)

Titan Express model was not supported as a chat model because LangChain
messages were not "translated" to a text prompt.

Co-authored-by: Guillem Orellana Trullols <guillem.orellana_trullols@siemens.com>

libs/community/langchain_community/llms/bedrock.py

@@ -272,10 +272,12 @@ class BedrockBase(BaseModel, ABC):
 
         try:
             response = self.client.invoke_model(
-                body=body, modelId=self.model_id, accept=accept, contentType=contentType
+                body=body,
+                modelId=self.model_id,
+                accept=accept,
+                contentType=contentType,
             )
             text = LLMInputOutputAdapter.prepare_output(provider, response)
-
         except Exception as e:
             raise ValueError(f"Error raised by bedrock service: {e}").with_traceback(
                 e.__traceback__