Refactor typing annotations in ChatManager and ChatAPI to use Union f…

…or older python.

lib/galaxy/managers/chat.py

@@ -1,4 +1,7 @@
-from typing import Optional
+from typing import (
+    Optional,
+    Union,
+)
 
 from fastapi import Path
 from sqlalchemy import (
@@ -59,7 +62,7 @@ def create(self, trans: ProvidesUserContext, job_id: JobIdPathParam, message: st
             trans.sa_session.commit()
         return chat_exchange
 
-    def get(self, trans: ProvidesUserContext, job_id: JobIdPathParam) -> ChatExchange | None:
+    def get(self, trans: ProvidesUserContext, job_id: JobIdPathParam) -> Union[ChatExchange, None]:
         """
         Returns the chat response from the DB based on the given job id.
         :param  job_id:      id of the job to load a response for from the DB

lib/galaxy/webapps/galaxy/api/chat.py

@@ -3,6 +3,7 @@
 """
 
 import logging
+from typing import Union
 
 from galaxy.config import GalaxyAppConfiguration
 from galaxy.exceptions import ConfigurationError
@@ -75,7 +76,7 @@ def feedback(
         job_id: JobIdPathParam,
         feedback: int,
         trans: ProvidesUserContext = DependsOnTrans,
-    ) -> int | None:
+    ) -> Union[int, None]:
         """Provide feedback on the chatbot response."""
         job = self.job_manager.get_accessible_job(trans, job_id)
         chat_response = self.chat_manager.set_feedback_for_job(trans, job.id, feedback)