add：

1.moderation tools
2.unittest

metagpt/tools/moderation.py

@@ -0,0 +1,40 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+"""
+@Time    : 2023/9/26 14:27
+@Author  : zhanglei
+@File    : moderation.py
+"""
+from typing import Union
+
+from metagpt.llm import LLM
+
+
+class Moderation:
+    def __init__(self):
+        self.llm = LLM()
+
+    def moderation(self, content: Union[str, list[str]]):
+        resp = []
+        if content:
+            moderation_results = self.llm.moderation(content=content)
+            results = moderation_results.results
+            for item in results:
+                resp.append(item.flagged)
+
+        return resp
+
+    async def amoderation(self, content: Union[str, list[str]]):
+        resp = []
+        if content:
+            moderation_results = await self.llm.amoderation(content=content)
+            results = moderation_results.results
+            for item in results:
+                resp.append(item.flagged)
+
+        return resp
+
+
+if __name__ == "__main__":
+    moderation = Moderation()
+    print(moderation.moderation(content=["I will kill you", "The weather is really nice today", "I want to hit you"]))