Fix Portal Serializer Typo

[vcai122]

No description provided.

[sentry-io]

🔍 Existing Issues For Review

Your pull request is modifying functions with the following pre-existing issues:

📄 File: backend/portal/serializers.py

Function	Unhandled Issue
is_valid	ValueError: invalid literal for int() with base 10: '' /api/portal/... Event Count: 12

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.83%. Comparing base (96a605c) to head (303136f).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #320      +/-   ##
==========================================
- Coverage   90.86%   90.83%   -0.04%     
==========================================
  Files          63       63              
  Lines        2661     2661              
==========================================
- Hits         2418     2417       -1     
- Misses        243      244       +1     

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