gh-104415: Fix refleak tests for typing.ByteString deprecation

Author: sobolevn

Lib/test/test_typing.py

@@ -6004,16 +6004,17 @@ def test_mutablesequence(self):
         self.assertNotIsInstance((), typing.MutableSequence)
 
     def test_bytestring(self):
+        _typing = import_fresh_module('typing')
         with self.assertWarns(DeprecationWarning):
-            from typing import ByteString
+            ByteString = _typing.ByteString
         with self.assertWarns(DeprecationWarning):
             self.assertIsInstance(b'', ByteString)
         with self.assertWarns(DeprecationWarning):
             self.assertIsInstance(bytearray(b''), ByteString)
         with self.assertWarns(DeprecationWarning):
             class Foo(ByteString): ...
         with self.assertWarns(DeprecationWarning):
-            class Bar(ByteString, typing.Awaitable): ...
+            class Bar(ByteString, _typing.Awaitable): ...
 
     def test_list(self):
         self.assertIsSubclass(list, typing.List)