Cakephp 5 (+ php 8.4, phpunit 11)

[didoda]

This updates dependencies and codebase to use cakephp 5.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (366016e) to head (b63f5b2).
Report is 17 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff             @@
##              master     #1237   +/-   ##
===========================================
  Coverage     100.00%   100.00%           
- Complexity      1352      1360    +8     
===========================================
  Files             97        97           
  Lines           5315      5376   +61     
===========================================
+ Hits            5315      5376   +61     

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