Bump nth-check and microbundle

Bumps [nth-check](https://github.com/fb55/nth-check) and [microbundle](https://github.com/developit/microbundle). These dependencies needed to be updated together.

Updates `nth-check` from 1.0.2 to 2.1.1
- [Release notes](https://github.com/fb55/nth-check/releases)
- [Commits](fb55/nth-check@v1.0.2...v2.1.1)

Updates `microbundle` from 0.12.4 to 0.15.0
- [Release notes](https://github.com/developit/microbundle/releases)
- [Changelog](https://github.com/developit/microbundle/blob/master/CHANGELOG.md)
- [Commits](developit/microbundle@v0.12.4...v0.15.0)

---
updated-dependencies:
- dependency-name: nth-check
  dependency-type: indirect
- dependency-name: microbundle
  dependency-type: direct:development
...

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

Author: dependabot[bot]