[3.9] bpo-37116: Use PEP 570 syntax for positional-only parameters. (GH-12620)

Turn deprecation warnings added in 3.8 into TypeError.
diff --git a/Lib/test/test_weakref.py b/Lib/test/test_weakref.py
index 6f15c03..ce5bbfc 100644
--- a/Lib/test/test_weakref.py
+++ b/Lib/test/test_weakref.py
@@ -1866,20 +1866,10 @@
         f()
         self.assertEqual(res, [((1, 2), {'func': 3, 'obj': 4})])
 
-        res = []
-        with self.assertWarns(DeprecationWarning):
-            f = weakref.finalize(a, func=fin, arg=1)
-        self.assertEqual(f.peek(), (a, fin, (), {'arg': 1}))
-        f()
-        self.assertEqual(res, [((), {'arg': 1})])
-
-        res = []
-        with self.assertWarns(DeprecationWarning):
-            f = weakref.finalize(obj=a, func=fin, arg=1)
-        self.assertEqual(f.peek(), (a, fin, (), {'arg': 1}))
-        f()
-        self.assertEqual(res, [((), {'arg': 1})])
-
+        with self.assertRaises(TypeError):
+            weakref.finalize(a, func=fin, arg=1)
+        with self.assertRaises(TypeError):
+            weakref.finalize(obj=a, func=fin, arg=1)
         self.assertRaises(TypeError, weakref.finalize, a)
         self.assertRaises(TypeError, weakref.finalize)