[Test] Disable failing async_task_priority test.

Author: mikeash

test/Concurrency/async_task_priority.swift

@@ -16,6 +16,8 @@
 // rdar://101077408 – Temporarily disable on watchOS simulator
 // UNSUPPORTED: DARWIN_SIMULATOR=watchos
 
+// REQUIRES: rdar105396748
+
 import Darwin
 @preconcurrency import Dispatch
 import StdlibUnittest