Update _imp to 3.14 (#14164)

Author: sobolevn

stdlib/@tests/stubtest_allowlists/py314.txt

@@ -3,7 +3,6 @@
 # ====================================================================
 
 _asyncio.all_tasks
-_imp.pyc_magic_number_token
 asyncio.eager_task_factory
 asyncio.tasks.eager_task_factory
 compression.gzip.GzipFile.readinto

stdlib/_imp.pyi

@@ -5,6 +5,8 @@ from importlib.machinery import ModuleSpec
 from typing import Any
 
 check_hash_based_pycs: str
+if sys.version_info >= (3, 14):
+    pyc_magic_number_token: int
 
 def source_hash(key: int, source: ReadableBuffer) -> bytes: ...
 def create_builtin(spec: ModuleSpec, /) -> types.ModuleType: ...