add discord rpc class

discord/models.py

@@ -0,0 +1,9 @@
+from pydantic import BaseModel
+from pypresence.types import ActivityType
+
+class DiscordRPCUpdatePayload(BaseModel):
+    title: str
+    subtitle: str
+    image_url: str
+    details: str
+    activity_type: ActivityType