build(deps): bump scratch-vm

Bumps [scratch-vm](https://github.com/LLK/scratch-vm) from 0.2.0-prerelease.20210601191643 to 0.2.0-prerelease.20210615010833.
- [Release notes](https://github.com/LLK/scratch-vm/releases)
- [Commits](https://github.com/LLK/scratch-vm/compare/0.2.0-prerelease.20210601191643...0.2.0-prerelease.20210615010833

)

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