Normal install of transformers & datasets

I think we no longer need the latest `master` from source.

dev/requirements.txt

@@ -1,8 +1,8 @@
 requests
 -f https://storage.googleapis.com/jax-releases/libtpu_releases.html
 jax[tpu]>=0.2.16
--e git+https://github.com/huggingface/transformers.git@master#egg=transformers
--e git+https://github.com/huggingface/datasets.git@master#egg=datasets
+transformers
+datasets
 flax
 jupyter
 wandb