sre_compile: use TypeIs (#15263)

Author: JelleZijlstra

stdlib/sre_compile.pyi

@@ -2,14 +2,11 @@ from re import Pattern
 from sre_constants import *
 from sre_constants import _NamedIntConstant
 from sre_parse import SubPattern
-from typing import Any, Final, Literal, overload
-from typing_extensions import TypeGuard
+from typing import Any, Final
+from typing_extensions import TypeIs
 
 MAXCODE: Final[int]
 
 def dis(code: list[_NamedIntConstant]) -> None: ...
-@overload
-def isstring(obj: str | bytes) -> Literal[True]: ...
-@overload
-def isstring(obj: object) -> TypeGuard[str | bytes]: ...
+def isstring(obj: object) -> TypeIs[str | bytes]: ...
 def compile(p: str | bytes | SubPattern, flags: int = 0) -> Pattern[Any]: ...