Bump vscode-extension-tester from 7.3.2 to 8.3.1

Bumps [vscode-extension-tester](https://github.com/redhat-developer/vscode-extension-tester/tree/HEAD/packages/extester) from 7.3.2 to 8.3.1.
- [Release notes](https://github.com/redhat-developer/vscode-extension-tester/releases)
- [Commits](https://github.com/redhat-developer/vscode-extension-tester/commits/v8.3.1/packages/extester)

---
updated-dependencies:
- dependency-name: vscode-extension-tester
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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