Unsubscribe from push notifications on logout

Closes: https://github.com/damus-io/damus/issues/1707
Changelog-Fixed: Fixed issue where users continue to receive push notifications after logout
Signed-off-by: Daniel D’Aquino <daniel@daquino.me>

damus/Models/DamusState.swift

@@ -175,6 +175,9 @@ class DamusState: HeadlessDamusState {
 
     func close() {
         print("txn: damus close")
+        Task {
+            try await self.push_notification_client.revoke_token()
+        }
         wallet.disconnect()
         pool.close()
         ndb.close()