Feedstocks that pin pytorch-cpu

We should clean these up, because they're preventing users from picking CUDA-enabled pytorch for no good reason:

* [x] https://github.com/conda-forge/bert-extractive-summarizer-feedstock/issues/1
* [x] https://github.com/conda-forge/eeyore-feedstock/issues/1
* [x] https://github.com/conda-forge/isofit-feedstock/issues/56
* [x] https://github.com/conda-forge/htm-pytorch-feedstock/issues/1
* [x] https://github.com/conda-forge/nannos-feedstock/issues/19
* [x] https://github.com/conda-forge/nlpaug-feedstock/pull/7
* [x] https://github.com/conda-forge/pydrobert-kaldi-feedstock/issues/5
* [x] https://github.com/conda-forge/pytorch-pretrained-bert-feedstock/issues/16
* [x] https://github.com/conda-forge/sagemaker-pytorch-serving-container-feedstock/issues/44
* [x] https://github.com/conda-forge/sparktorch-feedstock/issues/2
* [x] https://github.com/conda-forge/torchbiggraph-feedstock/issues/3
* [x] https://github.com/conda-forge/yews-feedstock/issues/6

# Dead feedstocks

* [allennlp-models](https://github.com/conda-forge/allennlp-models-feedstock/blob/27fa284ce0248a44ad09e410023a30b834b3c971/recipe/meta.yaml#L39)
* [sagemaker-pytorch-container](https://github.com/conda-forge/sagemaker-pytorch-container-feedstock/blob/e8715a2c47766e6c2f99816da9c3d959c3fc2536/recipe/meta.yaml#L28)

Found by this [search](https://github.com/search?q=org%3Aconda-forge+%2F-+pytorch-%5Bcg%5Dpu%2F+path%3Arecipe%2F*.yaml&type=code)