chore(deps): bump bson from 1.1.1 to 1.1.6 in /example/mongo (#183)

Bumps [bson](https://github.com/mongodb/js-bson) from 1.1.1 to 1.1.6.
- [Release notes](https://github.com/mongodb/js-bson/releases)
- [Changelog](https://github.com/mongodb/js-bson/blob/v1.1.6/HISTORY.md)
- [Commits](https://github.com/mongodb/js-bson/commits/v1.1.6)

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Author: dependabot[bot]