pin run-gemini-cli gha to v0.1.20

[QuanZhang-William]

Currently, the workflow example points to the floating@main version of run-gemini-cli GHA.

This commit updates the example to point to the pinned version of it (v0.1.20) for best practice.

[gemini-code-assist]

Note

Gemini is unable to generate a summary for this pull request due to the file types involved not being currently supported.

[github-actions]

🤖 Hi @QuanZhang-William, I've received your request, and I'm working on it now! You can track my progress in the logs for more details.

[github-actions]

## 📋 Review Summary

This pull request pins the version of the run-gemini-cli GitHub Action. This is a good practice for ensuring workflow stability and security. The review identified a potential typo in the specified version number.

🔍 General Feedback

• Pinning GitHub Actions to a specific version is a great security best practice.
• There's a version mismatch between the PR description and the code. Please ensure the correct version is used.

[github-actions]

## 📋 Security Analysis Summary

This pull request improves the security of the CI/CD pipeline by pinning the version of the run-gemini-cli GitHub Action. This is a recommended security practice to prevent supply chain attacks. The changes are beneficial and do not introduce any security vulnerabilities.

🔍 General Feedback

• No security vulnerabilities were found in this pull request.
• Pinning GitHub Actions to a specific version is a great security practice.

[QuanZhang-William]

Part of #133.