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 rules so updates are consolidated into fewer PRs, matching the configuration from yiisoft/package-template.

Changes:

• Group all github-actions updates into a single Dependabot PR.
• Group all Composer dependency updates into a single Dependabot PR.
• Fix the YAML indentation/order in the Composer update config while adding grouping.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (51d2919) to head (1b22202).

Additional details and impacted files

@@             Coverage Diff             @@
##              master      #405   +/-   ##
===========================================
  Coverage     100.00%   100.00%           
  Complexity       188       188           
===========================================
  Files             11        11           
  Lines            509       509           
===========================================
  Hits             509       509           

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.