reconfigure dependabot to group updates and run monthly

[jsandas]

This pull request updates the Dependabot configuration to reduce the frequency of dependency update checks and to group updates together for easier management.

Dependabot configuration changes:

• Changed the update schedule for gomod, github-actions, and docker dependencies from weekly to monthly to reduce noise from frequent pull requests.
• Added grouping for each ecosystem so that all updates are bundled together in a single pull request, making dependency management more efficient.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 77.01%. Comparing base (8f9427b) to head (8fdcc9e).
⚠️ Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #56      +/-   ##
==========================================
+ Coverage   76.35%   77.01%   +0.65%     
==========================================
  Files          15       15              
  Lines        1053      770     -283     
==========================================
- Hits          804      593     -211     
+ Misses        201      129      -72     
  Partials       48       48              

Flag	Coverage Δ
unittests	77.01% <ø> (+0.65%)	⬆️

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