fix: change num_code validation to maxLength(3)

[KilianTrunk]

No description provided.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.27%. Comparing base (2b08899) to head (65e4fff).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main      #21      +/-   ##
============================================
+ Coverage     83.24%   83.27%   +0.02%     
+ Complexity      261      260       -1     
============================================
  Files            31       31              
  Lines          1355     1369      +14     
============================================
+ Hits           1128     1140      +12     
- Misses          227      229       +2     

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