MistralAiChatModel returns an error if MessageChatMemoryAdvisor is used

[FabioAng71]

Bug description
If I use MistralAiChatModel with MessageChatMemoryAdvisor + InMemoryChatMemory, at the second iteration, I get the following erorr:
Unexpected role 'system' after role 'assistant'

At the second iteration the system role appears after the previous user role and assistant role messages and before the current user role message.

"messages": [
    {
      "content": "first user message is here",
      "role": "user"
    },
    {
      "content": "first assistant message is here",
      "role": "assistant"
    },
    {
      "content": "   You are an assistant helping people to buy tickets for trains, give the answer with the same language of the request.\n   The answer must be formated as MarkDown.\n",
      "role": "system"
    },
    {
      "content": "currentuser message is here",
      "role": "user"
    }
  ]

Environment
Spring AI 1.0.0-M6, Java version 21

Steps to reproduce
add the following fragment to the pom.xml

        <dependency>
            <groupId>org.springframework.ai</groupId>
            <artifactId>spring-ai-mistral-ai-spring-boot-starter</artifactId>
        </dependency>

use the following fragment of code

ChatClient.Builder builder
        chatClient = builder
                .defaultAdvisors(new MessageChatMemoryAdvisor(new InMemoryChatMemory()))
                .build();

Expected behavior
MistralAi LLM wants the system role to be the first one and this can be a general rule for all LLM.