Restore stubtest 0.930 (#6663)

stdlib/_imp.pyi

@@ -1,7 +1,11 @@
+import sys
 import types
 from importlib.machinery import ModuleSpec
 from typing import Any
 
+if sys.version_info >= (3, 7):
+    check_hash_based_pycs: str
+
 def create_builtin(__spec: ModuleSpec) -> types.ModuleType: ...
 def create_dynamic(__spec: ModuleSpec, __file: Any = ...) -> None: ...
 def acquire_lock() -> None: ...