fix categorize agent input content not format error (#4842)

### What problem does this PR solve?

Fix categorize agent input content not format error

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

Co-authored-by: wangrui <wangrui@haima.me>

agent/component/categorize.py

@@ -80,6 +80,7 @@ class Categorize(Generate, ABC):
 
     def _run(self, history, **kwargs):
         input = self.get_input()
+        input = " - ".join(input["content"]) if "content" in input else ""
         chat_mdl = LLMBundle(self._canvas.get_tenant_id(), LLMType.CHAT, self._param.llm_id)
         ans = chat_mdl.chat(self._param.get_prompt(input), [{"role": "user", "content": "\nCategory: "}],
                             self._param.gen_conf())