Bump microbundle from 0.14.2 to 0.15.1

Bumps [microbundle](https://github.com/developit/microbundle) from 0.14.2 to 0.15.1.
- [Release notes](https://github.com/developit/microbundle/releases)
- [Changelog](https://github.com/developit/microbundle/blob/master/CHANGELOG.md)
- [Commits](developit/microbundle@v0.14.2...v0.15.1)

---
updated-dependencies:
- dependency-name: microbundle
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]