Fix mistake in barry_as_FLUFL test (GH-31392)

Use assertEqual(), not assertTrue(lineno, 2)
diff --git a/Lib/test/test_flufl.py b/Lib/test/test_flufl.py
index 0ff54aa..a81a4d4 100644
--- a/Lib/test/test_flufl.py
+++ b/Lib/test/test_flufl.py
@@ -17,7 +17,7 @@
         self.assertIn('2 != 3', cm.exception.text)
         self.assertEqual(cm.exception.filename, '<FLUFL test>')
 
-        self.assertTrue(cm.exception.lineno, 2)
+        self.assertEqual(cm.exception.lineno, 2)
         # The old parser reports the end of the token and the new
         # parser reports the start of the token
         self.assertEqual(cm.exception.offset, 3)