Fix `tokenizer` type annotation in `pipeline(...)` (#17500)

I think you mean to accept either an instance of `PreTrainedTokenizer` or `PreTrainedTokenizerFast` inside of the `pipeline(...)` factory function, if the `tokenizer` argument isn't a `str`.

src/transformers/pipelines/__init__.py

@@ -29,6 +29,7 @@ from ..models.auto.configuration_auto import AutoConfig
 from ..models.auto.feature_extraction_auto import FEATURE_EXTRACTOR_MAPPING, AutoFeatureExtractor
 from ..models.auto.tokenization_auto import TOKENIZER_MAPPING, AutoTokenizer
 from ..tokenization_utils import PreTrainedTokenizer
+from ..tokenization_utils_fast import PreTrainedTokenizerFast
 from ..utils import http_get, is_tf_available, is_torch_available, logging
 from .audio_classification import AudioClassificationPipeline
 from .automatic_speech_recognition import AutomaticSpeechRecognitionPipeline
@@ -373,7 +374,7 @@ def pipeline(
     task: str = None,
     model: Optional = None,
     config: Optional[Union[str, PretrainedConfig]] = None,
-    tokenizer: Optional[Union[str, PreTrainedTokenizer]] = None,
+    tokenizer: Optional[Union[str, PreTrainedTokenizer, PreTrainedTokenizerFast]] = None,
     feature_extractor: Optional[Union[str, PreTrainedFeatureExtractor]] = None,
     framework: Optional[str] = None,
     revision: Optional[str] = None,