build(deps-dev): bump scratch-vm

Bumps [scratch-vm](https://github.com/LLK/scratch-vm) from 0.2.0-prerelease.20200616200729 to 0.2.0-prerelease.20200618162938.
- [Release notes](https://github.com/LLK/scratch-vm/releases)
- [Commits](https://github.com/LLK/scratch-vm/commits)

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

Author: dependabot-preview[bot]

package-lock.json

@@ -114,7 +114,7 @@
     "scratch-render": "0.1.0-prerelease.20200617185826",
     "scratch-storage": "1.3.3",
     "scratch-svg-renderer": "0.2.0-prerelease.20200610220938",
-    "scratch-vm": "0.2.0-prerelease.20200616200729",
+    "scratch-vm": "0.2.0-prerelease.20200618162938",
     "selenium-webdriver": "3.6.0",
     "startaudiocontext": "1.2.1",
     "style-loader": "^0.23.0",