Bump boto3 from 1.9.159 to 1.9.160
Bump boto3 from 1.9.159 to 1.9.160

Bumps [boto3](https://github.com/boto/boto3) from 1.9.159 to 1.9.160.
- [Release notes](https://github.com/boto/boto3/releases)
- [Changelog](https://github.com/boto/boto3/blob/develop/CHANGELOG.rst)
- [Commits](https://github.com/boto/boto3/compare/1.9.159...1.9.160)
mozilla-services/kinto-dist,Kinto/kinto-dist,mozilla-services/kinto-dist,Kinto/kinto-dist