Handle other skill option

[MaartenS11]

This pr adds correct handling for the other skill option in the tally form. Previously a student selecting "Other" would get Skill("Other"). With this pr the tally form deserializer will look at the correct field on the tally form to get the name of that other skill and add that skill into the skill list.

Checklist:

• I've updated the existing tests to test this behavior

[codecov]

Codecov Report

Merging #258 (6d9c855) into development (c1d7d04) will decrease coverage by 0.14%.
The diff coverage is 87.50%.

@@                Coverage Diff                @@
##             development     #258      +/-   ##
=================================================
- Coverage          95.84%   95.70%   -0.15%     
  Complexity           229      229              
=================================================
  Files                 44       44              
  Lines                602      605       +3     
  Branches              43       44       +1     
=================================================
+ Hits                 577      579       +2     
  Misses                15       15              
- Partials              10       11       +1     

Flag	Coverage Δ
all_tests	95.70% <87.50%> (-0.15%)	⬇️

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Impacted Files	Coverage Δ
...n/kotlin/be/osoc/team1/backend/entities/Student.kt	95.23% <ø> (ø)
...in/be/osoc/team1/backend/util/TallyDeserializer.kt	96.07% <87.50%> (-1.84%)	⬇️

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