[3.13] gh-128617: Fix test_typing.test_readonly_inheritance (GH-128618) (#128622)

gh-128617: Fix `test_typing.test_readonly_inheritance` (GH-128618)
(cherry picked from commit 971a52b)

Co-authored-by: sobolevn <[email protected]>

Author: miss-islington

Lib/test/test_typing.py

@@ -8829,13 +8829,13 @@ class Child1(Base1):
         self.assertEqual(Child1.__mutable_keys__, frozenset({'b'}))
 
         class Base2(TypedDict):
-            a: ReadOnly[int]
+            a: int
 
         class Child2(Base2):
-            b: str
+            b: ReadOnly[str]
 
-        self.assertEqual(Child1.__readonly_keys__, frozenset({'a'}))
-        self.assertEqual(Child1.__mutable_keys__, frozenset({'b'}))
+        self.assertEqual(Child2.__readonly_keys__, frozenset({'b'}))
+        self.assertEqual(Child2.__mutable_keys__, frozenset({'a'}))
 
     def test_cannot_make_mutable_key_readonly(self):
         class Base(TypedDict):