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

Copilot couldn't run its full agentic review because no GitHub Actions runner was available. Make sure your repository has a runner available to run Copilot's review, or add a copilot-setup-steps.yml file specifying one with the runs-on attribute. See the docs for more details.

Adds Dependabot grouping so updates are bundled into fewer PRs, matching the referenced template configuration.

Changes:

• Group all GitHub Actions updates into a single Dependabot PR.
• Group all Composer dependency updates into a single Dependabot PR.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.83%. Comparing base (2d41670) to head (9e758a2).

Additional details and impacted files

@@            Coverage Diff            @@
##             master     #120   +/-   ##
=========================================
  Coverage     99.83%   99.83%           
  Complexity      245      245           
=========================================
  Files            16       16           
  Lines           622      622           
=========================================
  Hits            621      621           
  Misses            1        1           

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