[interpolatable] Remove obsolete comment

Well, it won't be true anymore when varc-table branch merges.

Tests/varLib/interpolatable_test.py

@@ -258,8 +258,6 @@ class InterpolatableTest(unittest.TestCase):
         input_path = self.get_test_input(
             "..", "..", "ttLib", "data", "varc-ac00-ac01.ttf"
         )
-        # This particular test font which was generated by machine-learning
-        # exhibits an "error" in one of the masters; it's a false-positive.
         # Just make sure the code runs.
         interpolatable_main((input_path,))