Group Dependabot updates

[samdark]

Replicates the Dependabot grouping configuration from yiisoft/package-template so GitHub Actions updates are grouped into a single PR and Composer dependency updates are grouped into a single PR.

[Copilot]

Pull request overview

Note

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Adds Dependabot grouping so updates are consolidated into fewer PRs (one for GitHub Actions and one for Composer), matching the referenced yiisoft/package-template configuration.

Changes:

• Group all github-actions dependency updates into a single Dependabot PR.
• Group all Composer dependency updates into a single Dependabot PR.
• Fix/normalize YAML indentation for the Composer schedule block to ensure valid configuration structure.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (57fdc57) to head (fcd081b).

Additional details and impacted files

@@             Coverage Diff             @@
##              master      #149   +/-   ##
===========================================
  Coverage     100.00%   100.00%           
  Complexity       165       165           
===========================================
  Files             11        11           
  Lines            454       454           
===========================================
  Hits             454       454           

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