API: Text Normalization

The apply_text_normalizationparameter has been added to the text to speech endpoints.

This parameter controls text normalization with three modes: 'auto', 'on', and 'off'. When set to 'auto', the system will automatically decide whether to apply text normalization (e.g., spelling out numbers). With 'on', text normalization will always be applied, while with 'off', it will be skipped. It cannot be turned on for 'eleven_turbo_v2_5' model.