Fix undefined name 'wer' in character_error_rate test

Co-authored-by: wannaphong <8536487+wannaphong@users.noreply.github.com>

Author: Copilot

tests/extra/testx_benchmarks.py

@@ -394,4 +394,3 @@ def test_character_error_rate_deletions(self):
         # CER should be > 0 due to deletion
         self.assertGreater(cer, 0.0)
         self.assertLess(cer, 1.0)
-        self.assertGreater(wer, 0.0)