ci: add dependabot

[Cuiyus]

No description provided.

[greptile-apps]

Greptile Summary

Adds Dependabot v2 configuration to automatically update GitHub Actions dependencies. The configuration is well-structured with weekly updates scheduled for Mondays at 02:00 Asia/Shanghai time, appropriate labels (dependencies, github-actions), and a commit message prefix of ci that aligns with the repository's conventional commit standards.

Key configuration details:

• Updates limited to 5 open PRs at a time to avoid overwhelming reviewers
• Schedule timing (Monday 02:00 Asia/Shanghai) provides a good start-of-week review cadence
• Commit message format matches the repository's conventions (uses ci prefix)

Considerations:

• The repository also contains Python dependencies (pyproject.toml) and pre-commit hooks (.pre-commit-config.yaml) that could benefit from Dependabot updates in future iterations
• Current focus on GitHub Actions only is a reasonable first step

Confidence Score: 5/5

• This PR is safe to merge with no risks - it only adds a configuration file
• The Dependabot configuration is syntactically correct, follows v2 schema standards, and uses reasonable settings (weekly schedule, 5 PR limit, appropriate labels). The commit message prefix ci aligns with the repository's conventional commit standards seen in .pre-commit-config.yaml. No execution risk as it's purely declarative configuration.
• No files require special attention

Important Files Changed

Filename	Overview
.github/dependabot.yml	Adds Dependabot configuration for GitHub Actions with weekly updates on Mondays at 02:00 Asia/Shanghai time

_{Last reviewed commit: e851b7d}

[egolearner]

LGTM