DLPipelines: deprecated in favor of FastAI.jl

DLPipelines.jl has been deprecated, and all of its functionality has been moved to FastAI.jl.

DLPipelines.jl is an interface for defining deep learning data pipelines. This includes every data transformation beside the model itself: preprocessing and augmenting the data before feeding it into the model, and decoding the model's outputs to targets.

It is used in FastAI.jl to provide an easy-to-use interface for common learning tasks.