chore: add github-actions grouping to dependabot config

[Copilot]

Pull Request

Description

BuildMark's dependabot config was missing the groups setting for GitHub Actions updates (present in TemplateDotNetTool), causing each action to generate its own PR. This adds grouping consistent with the existing NuGet grouping and the template pattern.

Change:

• .github/dependabot.yml — add github-actions-dependencies group to the github-actions ecosystem entry:

  - package-ecosystem: "github-actions"
    ...
    groups:
      github-actions-dependencies:
        patterns:
          - "*"

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Code quality improvement

Related Issues

Pre-Submission Checklist

Before submitting this pull request, ensure you have completed the following:

Build and Test

• Code builds successfully: dotnet build --configuration Release
• All tests pass: dotnet test --configuration Release
• Code produces zero warnings

Code Quality

• Code formatting is correct: dotnet format --verify-no-changes
• New code has appropriate XML documentation comments
• Static analyzer warnings have been addressed

Quality Checks

Please run the following checks before submitting:

• Spell checker passes: cspell "**/*.{md,cs}"
• Markdown linter passes: markdownlint "**/*.md"
• YAML linter passes: yamllint '**/*.{yml,yaml}'

Testing

• Added unit tests for new functionality
• Updated existing tests if behavior changed
• All tests follow the AAA (Arrange, Act, Assert) pattern
• Test coverage is maintained or improved

Documentation

• Updated README.md (if applicable)
• Updated ARCHITECTURE.md (if applicable)
• Added code examples for new features (if applicable)
• Updated requirements.yaml (if applicable)

Additional Notes

Configuration-only change. No code or tests affected.

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