improve typing

discord/models.py

@@ -1,5 +1,6 @@
 from pydantic import BaseModel
 from pypresence.types import ActivityType
+from typing import Optional
 
 
 class DiscordRPCUpdatePayload(BaseModel):
@@ -8,6 +9,6 @@ class DiscordRPCUpdatePayload(BaseModel):
     subtitle: str
     image_url: str
     details: str
-    start: int | None
-    end: int | None
+    start: Optional[int]
+    end: Optional[int]
     activity_type: ActivityType