Change the role to "user" in format function of ollama chat model

src/agentscope/models/ollama_model.py

@@ -359,7 +359,7 @@ def format(
         system_content = "\n".join(system_content_template)
 
         system_message = {
-            "role": "system",
+            "role": "user",
             "content": system_content,
         }