Raise ValueError in phone validator

[armanddidierjean]

to let FastAPI return Pydantic ValidationError instead of crashing

Checklist

• Created tests which fail without the change (if possible)
• All tests passing
• Extended the documentation, if necessary

[codecov]

Codecov Report

Attention: Patch coverage is 33.33333% with 4 lines in your changes missing coverage. Please review.

Project coverage is 81.52%. Comparing base (09ed49e) to head (7739461).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
app/utils/validators.py	33.33%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #552      +/-   ##
==========================================
- Coverage   81.53%   81.52%   -0.02%     
==========================================
  Files         128      128              
  Lines        9943     9942       -1     
==========================================
- Hits         8107     8105       -2     
- Misses       1836     1837       +1     

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