Bump rails from 5.1.4 to 5.1.6
Bump rails from 5.1.4 to 5.1.6

Bumps [rails](https://github.com/rails/rails) from 5.1.4 to 5.1.6.
- [Release notes](https://github.com/rails/rails/releases)
- [Commits](https://github.com/rails/rails/compare/v5.1.4...v5.1.6)

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
openpolitics/votebot,openpolitics/votebot,openpolitics/votebot