[smollm3] add tokenizer mapping for smollm3 (#39271)

add tok mapping to smollm3

Author: gante

src/transformers/models/auto/tokenization_auto.py

@@ -580,6 +580,7 @@
                 "GemmaTokenizerFast" if is_tokenizers_available() else None,
             ),
         ),
+        ("smollm3", (None, "PreTrainedTokenizerFast" if is_tokenizers_available() else None)),
         ("speech_to_text", ("Speech2TextTokenizer" if is_sentencepiece_available() else None, None)),
         ("speech_to_text_2", ("Speech2Text2Tokenizer", None)),
         ("speecht5", ("SpeechT5Tokenizer" if is_sentencepiece_available() else None, None)),