chore: update CI dependencies to latest versions

[autopilot-project-manager]

CI Dependency Updates

This PR updates the following GitHub Actions dependencies to their latest versions:

• actions/checkout: v4 → v6
• actions/checkout: v4 → v6

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This PR was automatically created by GitHub PM Bot.

[autopilot-project-manager]

Autopilot PR Check Issues

The following potential issues were detected in this PR:

.github/workflows/ci.yml

• 🎭 Line 14 (Mock Implementation): The version actions/checkout@v6 does not exist yet (current version is v4). This looks like a speculative or mock version number.

  - uses: actions/checkout@v6
  

• 🎭 Line 25 (Mock Implementation): The version actions/checkout@v6 does not exist yet (current version is v4). This looks like a speculative or mock version number.

  - uses: actions/checkout@v6
  

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Please review and address these issues before merging.