Issue #26621: Remove unnecessary test.

Author: skrah

Lib/test/test_decimal.py

@@ -4173,7 +4173,6 @@ def test_module_attributes(self):
         self.assertTrue(P.HAVE_THREADS is True or P.HAVE_THREADS is False)
 
         self.assertEqual(C.__version__, P.__version__)
-        self.assertEqual(C.__libmpdec_version__, P.__libmpdec_version__)
 
         self.assertEqual(dir(C), dir(P))