Add Dependabot configuration and CodeQL analysis workflow

[pmalarme]

This pull request introduces automated dependency and security management for the repository by adding configuration files for Dependabot and CodeQL. These additions help keep dependencies up-to-date and enable regular code analysis for vulnerabilities.

Dependency management:

• Added .github/dependabot.yml to enable weekly updates of GitHub Actions dependencies, scheduled for Sundays, with appropriate labeling for easier tracking.

Security analysis automation:

• Added .github/workflows/codeql-analysis.yaml workflow to run CodeQL analysis on pushes, pull requests, and a weekly schedule, targeting the actions language. This helps identify security vulnerabilities in GitHub Actions workflows.

[github-advanced-security]

This pull request sets up GitHub code scanning for this repository. Once the scans have completed and the checks have passed, the analysis results for this pull request branch will appear on this overview. Once you merge this pull request, the 'Security' tab will show more code scanning analysis results (for example, for the default branch). Depending on your configuration and choice of analysis tool, future pull requests will be annotated with code scanning analysis results. For more information about GitHub code scanning, check out the documentation.