update compat helper

[willtebbutt]

Upgrades compat helper to the latest version of the GHA

[devmotion]

Looks good to me, we should definitely use version 3. I started a CompatHelper run with the changes in this PR to see if everything works correctly: https://github.com/JuliaGaussianProcesses/GPLikelihoods.jl/actions/runs/4252591667/jobs/7396376500

Feel free to merge if it passes and my comment below is addressed 🙂

[codecov]

Codecov Report

Base: 96.37% // Head: 96.37% // No change to project coverage 👍

Coverage data is based on head (f40bdee) compared to base (4b33f7a).
Patch has no changes to coverable lines.

Additional details and impacted files

@@           Coverage Diff           @@
##           master      #97   +/-   ##
=======================================
  Coverage   96.37%   96.37%           
=======================================
  Files          10       10           
  Lines         138      138           
=======================================
  Hits          133      133           
  Misses          5        5           

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report at Codecov.
📢 Do you have feedback about the report comment? Let us know in this issue.

[willtebbutt]

Thanks for the review @devmotion . Will merge when CI passes