Update GitHub workflows: remove CompatHelper, add Julia dependabot

[Krastanov-agent]

⚠️ Important: This enables dependabot only for the top-level Julia package. If there are any other sub-packages in subfolders, they will not be tracked by dependabot and may need separate configuration.

CC @Krastanov

Summary

• Remove CompatHelper workflows (replaced by dependabot)
• Add/update dependabot.yml with Julia and GitHub Actions ecosystems
• Julia dependabot support is now stable and preferred over CompatHelper

Changes

• Deleted any CompatHelper workflow files from .github/workflows/
• Updated/created .github/dependabot.yml with Julia and GitHub Actions ecosystem configurations
• Set weekly update schedule for Julia dependencies and GitHub Actions

Test plan

• Verify no CompatHelper workflows remain in .github/workflows/
• Confirm dependabot.yml has proper Julia and GitHub Actions ecosystem configurations
• Check that dependabot starts working after merge (may take up to 24 hours)

🤖 Generated with Claude Code

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Script source: https://gist.github.com/Krastanov-agent/2b049684a01788458c399e9441bb264a

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.40%. Comparing base (aabbbbb) to head (0bfd2ed).
⚠️ Report is 22 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #92      +/-   ##
==========================================
+ Coverage   94.29%   97.40%   +3.11%     
==========================================
  Files          10       10              
  Lines         578      579       +1     
==========================================
+ Hits          545      564      +19     
+ Misses         33       15      -18     

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[Krastanov]

This PR should simplify the handling of compat updates, now that Julia is supported by dependabot. CompatHelper is not needed anymore. And dependabot does not stop after a few months of inactivity in the repository. There are a bunch of other minor quality of life improvements as well.

This PR was made by a bot, but now I am commenting as a human check on the bot that I endorse this PR and have checked its correctness.

This JuliaGraphs repo has its own active maintainers, thus I will not be merging this PR myself.

[hexaeder]

Thanks for the PR! May you tell your agent to also extend it to the /docs env? I haven't worked with the new dependabot style yet, not sure how to do that...

[Krastanov]

the docs should be included now