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.

Updates Dependabot configuration to group related dependency updates, reducing PR noise and aligning with yiisoft/package-template.

Changes:

• Group all GitHub Actions dependency 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 98.67%. Comparing base (ece48b6) to head (80e8574).

Additional details and impacted files

@@            Coverage Diff            @@
##             master      #53   +/-   ##
=========================================
  Coverage     98.67%   98.67%           
  Complexity      143      143           
=========================================
  Files             3        3           
  Lines           377      377           
=========================================
  Hits            372      372           
  Misses            5        5           

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