Bump microbundle from 0.12.2 to 0.12.3
Bump microbundle from 0.12.2 to 0.12.3

Bumps [microbundle](https://github.com/developit/microbundle) from 0.12.2 to 0.12.3.
- [Release notes](https://github.com/developit/microbundle/releases)
- [Commits](https://github.com/developit/microbundle/compare/0.12.2...0.12.3)

Signed-off-by: dependabot-preview[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
substantial/updeep,substantial/updeep