deps: Bump codecov-action from 4 to 5

[khvn26]

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• I have read the Contributing Guide.
• I have added information to docs/ if required so people know about the feature.
• I have filled in the "Changes" section below.
• I have filled in the "How did you test this code" section below.

Changes

In this PR, we attempt to fix the false negative project coverage reporting by Codecov.

How did you test this code?

This is a CI change.

[vercel]

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3 Skipped Deployments

Project	Deployment	Actions	Updated (UTC)
docs	Ignored		Feb 10, 2026 11:39am
flagsmith-frontend-preview	Ignored		Feb 10, 2026 11:39am
flagsmith-frontend-staging	Ignored		Feb 10, 2026 11:39am

[github-actions]

Docker builds report

Image	Build Status	Security report
ghcr.io/flagsmith/flagsmith-e2e:pr-6680	Finished ✅	Skipped
ghcr.io/flagsmith/flagsmith-frontend:pr-6680	Finished ✅	Results ✅
ghcr.io/flagsmith/flagsmith-api-test:pr-6680	Finished ✅	Skipped
ghcr.io/flagsmith/flagsmith-api:pr-6680	Finished ✅	Results ✅
ghcr.io/flagsmith/flagsmith:pr-6680	Finished ✅	Results ✅
ghcr.io/flagsmith/flagsmith-private-cloud:pr-6680	Finished ✅	Results ✅

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.22%. Comparing base (7d39204) to head (dcf7567).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6680   +/-   ##
=======================================
  Coverage   98.22%   98.22%           
=======================================
  Files        1313     1313           
  Lines       47481    47481           
=======================================
  Hits        46636    46636           
  Misses        845      845           

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