Update SonarQube plugin ref tag

[sophio-japharidze-sonarsource]

Pull Request Checklist

• I have read and followed the CONTRIBUTING.md guidelines.
• I have read and followed the Guidance for submissions involving paid services.
• My contribution adds a new instruction, prompt, agent, skill, or workflow file in the correct directory.
• The file follows the required naming convention.
• The content is clearly structured and follows the example format.
• I have tested my instructions, prompt, agent, skill, or workflow with GitHub Copilot.
• I have run npm start and verified that README.md is up to date.
• I am targeting the staged branch for this pull request.

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Description

Changes ref of the external SonarQube plugin from a commit sha to a release tag.

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Type of Contribution

• New instruction file.
• New prompt file.
• New agent file.
• New plugin.
• New skill file.
• New agentic workflow.
• Update to existing instruction, prompt, agent, plugin, skill, or workflow.
• Other (please specify):

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Additional Notes

Caused by #1774

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By submitting this pull request, I confirm that my contribution abides by the Code of Conduct and will be licensed under the MIT License.

[Copilot]

Pull request overview

Updates the SonarQube external plugin listing to use a stable release tag (instead of a now-missing commit SHA) so installs can reliably fetch the repository ref, addressing the failure described in #1774.

Changes:

• Updated the SonarQube plugin source.ref from a commit SHA to refs/tags/v2.0.0 in the external plugin registry.
• Regenerated/updated the corresponding entry in the generated marketplace file to keep it in sync.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
plugins/external.json	Switches SonarQube external plugin ref to refs/tags/v2.0.0 (immutable tag format aligns with repo validation rules).
.github/plugin/marketplace.json	Mirrors the SonarQube ref update so marketplace output remains consistent with plugins/external.json.

[aaronpowell]

We found another bug in the CLI that if you prefix with refs/tags it fails to check out (see #1783), so we have to just do the tag name.

[tomshafir-sonarsource]

We found another bug in the CLI that if you prefix with refs/tags it fails to check out (see #1783), so we have to just do the tag name.

@aaronpowell
Committed the requested changes

[sophio-japharidze-sonarsource]

@aaronpowell sorry there was a typo in the tag name 😭 I have opened #1834