OpenNMT-tf 2.30.0

Changes

• The model attribute ctranslate2_spec has been removed as it is no longer relevant with the new CTranslate2 converter
• The global gradient norm is no longer reported in TensorBoard because it was misleading: it did not take into account gradient accumulation and multi-GPU

New features

• Support TensorFlow 2.11 (note that the new Keras optimizers are not yet supported, if you are creating optimizers manually please use an optimizer in tf.keras.optimizers.legacy for now)
• Support CTranslate2 3.0
• Add training parameter pad_to_bucket_boundary to pad the batch length to a multiple of length_bucket_width (this is useful to reduce the number of recompilation with XLA)
• Integrate the scorers chrf and chrf++ from SacreBLEU

Fixes and improvements

• Fix error when training with Horovod and using an early stopping condition
• Fix error when using guided alignment with mixed precision