fix: make sure eic roles are populated correctly

[lwasser]

This fixes parsing of the EiC role (when it exists) i our review metadata population.
There were a few issues

✅ the field serializer and the validator were not setup to include packages_eic
✅ eic wasn't a role in our contrib_roles object for the review model so that field wasn't being processed. As such when Chiara added her name which was missing, it was deleted in the next bot update. This is now fixed

This pr doesn't have tests yet but we should add some integration tests that ensure contrib data are processed correctly. and then another test to check serialization to yaml

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.06%. Comparing base (fb5e6f1) to head (ea94efc).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #235      +/-   ##
==========================================
+ Coverage   73.99%   74.06%   +0.07%     
==========================================
  Files          10       10              
  Lines         669      671       +2     
  Branches       82       82              
==========================================
+ Hits          495      497       +2     
  Misses        166      166              
  Partials        8        8              

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