Bump @vscode/test-electron from 2.3.8 to 2.3.9

Bumps [@vscode/test-electron](https://github.com/Microsoft/vscode-test) from 2.3.8 to 2.3.9.
- [Changelog](https://github.com/microsoft/vscode-test/blob/main/CHANGELOG.md)
- [Commits](https://github.com/Microsoft/vscode-test/commits/v2.3.9)

---
updated-dependencies:
- dependency-name: "@vscode/test-electron"
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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Author: dependabot[bot]