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 by bundling GitHub Actions updates and Composer updates into dedicated PRs.

Changes:

• Adds a Dependabot group for GitHub Actions updates to combine them into a single PR.
• Adds a new Dependabot update entry for Composer (PHP) dependencies with grouping enabled.
• Configures Composer update strategy via versioning-strategy: increase-if-necessary.

---

💡 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 47.87%. Comparing base (cf8f535) to head (bb0085e).

Additional details and impacted files

@@            Coverage Diff            @@
##             master     #561   +/-   ##
=========================================
  Coverage     47.87%   47.87%           
  Complexity      506      506           
=========================================
  Files            44       44           
  Lines          1579     1579           
=========================================
  Hits            756      756           
  Misses          823      823           

☔ 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.