Fix case for `activations` attribute in nn.RNN ONNX export. (#19368)
Summary:
This PR addresses the https://github.com/pytorch/pytorch/issues/19366 issue.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/19368
Reviewed By: zrphercule
Differential Revision: D15043949
Pulled By: houseroad
fbshipit-source-id: 9b90410307d31bc5f2fd14aa0cdd33b22572ed7c
