Bump bl from 2.2.0 to 2.2.1 (#20)

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)

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