fix: make Google Vertex Chat Generator compatible with new ChatMessage (#1255)

* make Vertex compatible with new ChatMessage

* fmt

Author: anakin87

integrations/google_vertex/src/haystack_integrations/components/generators/google_vertex/chat/gemini.py

@@ -280,12 +280,10 @@ def _get_response(self, response_body: GenerationResponse) -> List[ChatMessage]:
                 # Remove content from metadata
                 metadata.pop("content", None)
                 if part._raw_part.text != "":
-                    replies.append(ChatMessage.from_assistant(content=part._raw_part.text, meta=metadata))
+                    replies.append(ChatMessage.from_assistant(part._raw_part.text, meta=metadata))
                 elif part.function_call:
                     metadata["function_call"] = part.function_call
-                    new_message = ChatMessage.from_assistant(
-                        content=json.dumps(dict(part.function_call.args)), meta=metadata
-                    )
+                    new_message = ChatMessage.from_assistant(json.dumps(dict(part.function_call.args)), meta=metadata)
                     new_message.name = part.function_call.name
                     replies.append(new_message)
         return replies