Bump bl from 2.2.0 to 2.2.1

Bumps [bl](https://github.com/rvagg/bl) from 2.2.0 to 2.2.1.
- [Release notes](https://github.com/rvagg/bl/releases)
- [Commits](rvagg/bl@v2.2.0...v2.2.1)

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

Author: dependabot[bot]