chore: add `maven` to dependabot

[vil02]

This PR will help to keep our pom.xml up to date.

• [x] I have read CONTRIBUTING.md.
• [x] This pull request is all my own work -- I have not plagiarized it.
• [x] All filenames are in PascalCase.
• [x] All functions and variable names follow Java naming conventions.
• [x] All new algorithms have a URL in their comments that points to Wikipedia or other similar explanations.
• [x] All new code is formatted with clang-format -i --style=file path/to/your/file.java

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 37.34%. Comparing base (4bb6455) to head (6e7b6c2).

Additional details and impacted files

@@            Coverage Diff            @@
##             master    #5123   +/-   ##
=========================================
  Coverage     37.34%   37.34%           
  Complexity     2350     2350           
=========================================
  Files           517      517           
  Lines         15622    15622           
  Branches       2971     2971           
=========================================
  Hits           5834     5834           
  Misses         9500     9500           
  Partials        288      288           

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