Update transformers requirement from <4.18,>=4.1 to >=4.1,<4.19 (#5617)

Updates the requirements on [transformers](https://github.com/huggingface/transformers) to permit the latest version.
- [Release notes](https://github.com/huggingface/transformers/releases)
- [Commits](huggingface/transformers@v4.1.0...v4.18.0)

---
updated-dependencies:
- dependency-name: transformers
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Dirk Groeneveld <dirkg@allenai.org>

requirements.txt

@@ -16,7 +16,7 @@ h5py
 scikit-learn
 scipy
 pytest
-transformers>=4.1,<4.18
+transformers>=4.1,<4.19
 sentencepiece
 dataclasses;python_version<'3.7'
 filelock>=3.3,<3.7