chore: drop Python 2 support

[khvn26]

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Changes

This removes an unused code path in settings/common.py.

How did you test this code?

Green CI will mean ok to merge as it's common settings.

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3 Skipped Deployments

Name	Status	Preview	Comments	Updated (UTC)
docs	⬜️ Ignored (Inspect)			Apr 8, 2025 7:40pm
flagsmith-frontend-preview	⬜️ Ignored (Inspect)			Apr 8, 2025 7:40pm
flagsmith-frontend-staging	⬜️ Ignored (Inspect)			Apr 8, 2025 7:40pm

[github-actions]

Docker builds report

Image	Build Status	Security report
ghcr.io/flagsmith/flagsmith-e2e:pr-5315	Finished ✅	Skipped
ghcr.io/flagsmith/flagsmith-api-test:pr-5315	Finished ✅	Skipped
ghcr.io/flagsmith/flagsmith-api:pr-5315	Finished ✅	Results ✅
ghcr.io/flagsmith/flagsmith-frontend:pr-5315	Finished ✅	Results ✅
ghcr.io/flagsmith/flagsmith:pr-5315	Finished ✅	Results ✅
ghcr.io/flagsmith/flagsmith-private-cloud:pr-5315	Finished ✅	Results ✅

[github-actions]

Uffizzi Preview deployment-62574 was deleted.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.52%. Comparing base (374a5f4) to head (ab26b29).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5315   +/-   ##
=======================================
  Coverage   97.52%   97.52%           
=======================================
  Files        1226     1226           
  Lines       42564    42559    -5     
=======================================
- Hits        41510    41507    -3     
+ Misses       1054     1052    -2     

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