Bump bootstrap from 3.4.0 to 3.4.1

Bumps [bootstrap](https://github.com/twbs/bootstrap) from 3.4.0 to 3.4.1.
- [Release notes](https://github.com/twbs/bootstrap/releases)
- [Commits](https://github.com/twbs/bootstrap/compare/v3.4.0...v3.4.1

)

Signed-off-by: dependabot[bot] <support@dependabot.com>
Signed-off-by: Roeland Jago Douma <roeland@famdouma.nl>