gh-128617: Fix test_typing.test_readonly_inheritance (#128618)

Author: sobolevn

Lib/test/test_typing.py

@@ -8912,13 +8912,13 @@ 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):