Callable activation function support for Transformer modules (Python) (#61355)
Summary:
Fixes Python part of https://github.com/pytorch/pytorch/issues/60747
Enhances the Python versions of `Transformer`, `TransformerEncoderLayer`, and `TransformerDecoderLayer` to support callables as their activation functions. The old way of specifying activation function still works as well.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/61355
Reviewed By: bdhirsh
Differential Revision: D29967302
Pulled By: jbschlosser
fbshipit-source-id: 8ee6f20083d49dcd3ab432a18e6ad64fe1e05705
