Fix FP16 inference in TextGenerationPipeline (#20913)
* add torch_dtype attribute to Pipeline
* Use torch_dtype to cast input tensor type in AutomaticSpeechRecognitionPipeline
* Fix code quality
* Add TextGenerationPipeline fp16 test
* Fix code quality
* Remove useless require in tests
Co-authored-by: Nicolas Patry <patry.nicolas@protonmail.com>
Co-authored-by: Nicolas Patry <patry.nicolas@protonmail.com>