Drop Python 3.8 branches (#13776)

stdlib/hmac.pyi

@@ -1,9 +1,8 @@
-import sys
-from _hashlib import _HashObject
+from _hashlib import _HashObject, compare_digest as compare_digest
 from _typeshed import ReadableBuffer, SizedBuffer
 from collections.abc import Callable
 from types import ModuleType
-from typing import AnyStr, overload
+from typing import overload
 from typing_extensions import TypeAlias
 
 _DigestMod: TypeAlias = str | Callable[[], _HashObject] | ModuleType
@@ -32,11 +31,3 @@ class HMAC:
     def copy(self) -> HMAC: ...
 
 def digest(key: SizedBuffer, msg: ReadableBuffer, digest: _DigestMod) -> bytes: ...
-
-if sys.version_info >= (3, 9):
-    from _hashlib import compare_digest as compare_digest
-else:
-    @overload
-    def compare_digest(a: ReadableBuffer, b: ReadableBuffer, /) -> bool: ...
-    @overload
-    def compare_digest(a: AnyStr, b: AnyStr, /) -> bool: ...