Minor tweaks (#11249)

### What problem does this PR solve?

Fix some IDE warnings

### Type of change

- [x] Refactoring

---------

Signed-off-by: Jin Hai <haijin.chn@gmail.com>

api/apps/dialog_app.py

@@ -154,15 +154,15 @@ def get_kb_names(kb_ids):
 @login_required
 def list_dialogs():
     try:
-        diags = DialogService.query(
+        conversations = DialogService.query(
             tenant_id=current_user.id,
             status=StatusEnum.VALID.value,
             reverse=True,
             order_by=DialogService.model.create_time)
-        diags = [d.to_dict() for d in diags]
-        for d in diags:
-            d["kb_ids"], d["kb_names"] = get_kb_names(d["kb_ids"])
-        return get_json_result(data=diags)
+        conversations = [d.to_dict() for d in conversations]
+        for conversation in conversations:
+            conversation["kb_ids"], conversation["kb_names"] = get_kb_names(conversation["kb_ids"])
+        return get_json_result(data=conversations)
     except Exception as e:
         return server_error_response(e)