build(deps): bump scratch-vm

Bumps [scratch-vm](https://github.com/LLK/scratch-vm) from 0.2.0-prerelease.20210226135205 to 0.2.0-prerelease.20210302015938.
- [Release notes](https://github.com/LLK/scratch-vm/releases)
- [Commits](https://github.com/LLK/scratch-vm/compare/0.2.0-prerelease.20210226135205...0.2.0-prerelease.20210302015938

)

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