feat: allow to submit category value_tag in /annotate route

[raphael0202]

Required to unlock openfoodfacts/hunger-games#721

[codecov]

Codecov Report

Merging #1269 (0b79829) into main (11ed428) will increase coverage by 0.13%.
Report is 1 commits behind head on main.
The diff coverage is 96.77%.

@@            Coverage Diff             @@
##             main    #1269      +/-   ##
==========================================
+ Coverage   56.39%   56.53%   +0.13%     
==========================================
  Files          77       77              
  Lines        7440     7465      +25     
==========================================
+ Hits         4196     4220      +24     
- Misses       3244     3245       +1     

Files	Coverage Δ
robotoff/app/core.py	91.07% <ø> (ø)
robotoff/insights/annotate.py	53.55% <100.00%> (+2.96%)	⬆️
robotoff/models.py	97.91% <ø> (ø)
robotoff/types.py	92.45% <100.00%> (ø)
robotoff/app/api.py	48.59% <90.00%> (+0.42%)	⬆️

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