Bump urllib3 from 1.25.6 to 1.25.8 in /bin/transformers

Bumps [urllib3](https://github.com/urllib3/urllib3) from 1.25.6 to 1.25.8.
- [Release notes](https://github.com/urllib3/urllib3/releases)
- [Changelog](https://github.com/urllib3/urllib3/blob/main/CHANGES.rst)
- [Commits](urllib3/urllib3@1.25.6...1.25.8)

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

Author: dependabot[bot]

bin/transformers/requirements-dev.txt

@@ -41,7 +41,7 @@ tensorflow-estimator==2.0.0
 termcolor==1.1.0
 torch==1.2.0
 tqdm==4.36.1
-urllib3==1.25.6
+urllib3==1.25.8
 wcwidth==0.1.7
 Werkzeug==0.16.0
 wrapt==1.11.2