gh-104533: Update test_ctypes.test_structures (#154091)

Author: vstinner

Lib/test/test_ctypes/test_structures.py

@@ -958,7 +958,7 @@ class Foo:
     def test_string_annotations(self):
         from test.test_ctypes import struct_str_ann
         Point = struct_str_ann.Point
-        fields = [['x', c_int], ['y', c_int]]
+        fields = [('x', c_int), ('y', c_int)]
         self.assertEqual(Point._fields_, fields)