repetiton_penalty and logits_bias just using logits_processors (#1004)

* refactor of repetition_penalty and logits_bias to use logits_processor

* nits

---------

Co-authored-by: Awni Hannun <awni@apple.com>

llms/tests/test_generate.py

@@ -46,7 +46,7 @@ class TestGenerate(unittest.TestCase):
             "hello",
             max_tokens=5,
             verbose=False,
-            logits_processor=logits_processor,
+            logits_processor=[logits_processor],
         )
         self.assertEqual(len(all_toks), len(init_toks) + 5)