chore: remove invalid and obsolete Dependabot filter

[Flash0ver]

Summary

Remove now obsolete, and also invalid in the first place, filter rule for Dependabot.

Remarks

Added in #5086, because Action gradle/actions/setup-gradle in version v6.0.0 changed the license of the the bundled 'gradle-actions-caching' component from MIT to a proprietary/commercial license.

However, v6.1.0 of the Action has added a non-default opt-in to replace this "Enhanced" Caching Component with a "Basic" open-source MIT-based version, to which we have switched to in #5130.

So the Dependabot ignore is no longer needed.
Also, it did not work in the first place!

[github-actions]

Semver Impact of This PR

⚪ None (no version bump detected)

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.06%. Comparing base (3d46788) to head (5e193bf).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5147      +/-   ##
==========================================
- Coverage   74.07%   74.06%   -0.01%     
==========================================
  Files         501      501              
  Lines       18111    18111              
  Branches     3521     3521              
==========================================
- Hits        13415    13414       -1     
  Misses       3837     3837              
- Partials      859      860       +1     

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