Group CodeQL action updates in Dependabot

[muir]

This PR groups CodeQL action updates in Dependabot to ensure that init/autobuild/analyze steps stay on the same version.

The init, autobuild, and analyze steps must stay on the same version, so they have to be bumped in a single pull request.

This change adds a groups configuration to .github/dependabot.yml that groups all github/codeql-action* updates together.

Related to: singlestore-labs/events#192

[cursor]

PR Summary

Low Risk
Only Dependabot grouping for GitHub Actions; no runtime or application code changes.

Overview
Dependabot’s github-actions entry now includes a codeql-action group that matches github/codeql-action* so init, autobuild, and analyze bumps land in one PR instead of separate daily updates.

That aligns with .github/workflows/codeql-analysis.yml, where those three steps must stay on the same version.

^{Reviewed by Cursor Bugbot for commit 3b59200. Configure here.}

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.35%. Comparing base (ef0e301) to head (3b59200).

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #60   +/-   ##
=======================================
  Coverage   85.35%   85.35%           
=======================================
  Files           6        6           
  Lines         280      280           
=======================================
  Hits          239      239           
  Misses         29       29           
  Partials       12       12           

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