Replace CompatHelper with Dependabot for Julia packages

[devmotion]

No description provided.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 72.39%. Comparing base (53dc188) to head (9c514f7).
⚠️ Report is 5 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #213   +/-   ##
=======================================
  Coverage   72.39%   72.39%           
=======================================
  Files          22       22           
  Lines        1007     1007           
=======================================
  Hits          729      729           
  Misses        278      278           

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[andreasnoack]

Is this the modern approach

[DilumAluthge]

CompatHelper is still maintained (for bug fixes and security issues), but we have begun encouraging folks to migrate to Dependabot, because:

1. It lets us offload a lot of the work onto GitHub.
2. It lets folks use the same tool (Dependabot) for multiple language ecosystems.

[devmotion]

The CompatHelper repo tells users

CompatHelper is now in maintenance mode. We recommend that users migrate to GitHub Dependabot

dependabot doesn't support private registries but for public packages it seems sufficient, eg DifferentiationInterface switched a while ago.

[DilumAluthge]

dependabot doesn't support private registries

True, but I'm hoping that we'll be able to add support for that in the future.