bpo-45859: Mark test_field_descriptor in test_collections as CPython-only (GH-29691)

(cherry picked from commit 4fad314)

Co-authored-by: Carl Friedrich Bolz-Tereick <cfbolz@gmx.de>

Author: cfbolz

Lib/test/test_collections.py

@@ -663,6 +663,7 @@ class Point(namedtuple('_Point', ['x', 'y'])):
         a.w = 5
         self.assertEqual(a.__dict__, {'w': 5})
 
+    @support.cpython_only
     def test_field_descriptor(self):
         Point = namedtuple('Point', 'x y')
         p = Point(11, 22)