Bump bootstrap from 3.3.7 to 3.4.1

Bumps [bootstrap](https://github.com/twbs/bootstrap) from 3.3.7 to 3.4.1.
- [Release notes](https://github.com/twbs/bootstrap/releases)
- [Commits](twbs/bootstrap@v3.3.7...v3.4.1)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]