Add 3.12 to CI

[matmair]

This PR (re) adds 3.12 to the CI in preparation for #8582

[netlify]

✅ Deploy Preview for inventree-web-pui-preview ready!

Name	Link
🔨 Latest commit	913cfbd
🔍 Latest deploy log	https://app.netlify.com/sites/inventree-web-pui-preview/deploys/676135134b007b00086bb600
😎 Deploy Preview	https://deploy-preview-8592--inventree-web-pui-preview.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.
Lighthouse	1 paths audited Performance: 100 (🟢 up 1 from production) Accessibility: 86 (no change from production) Best Practices: 100 (no change from production) SEO: 78 (no change from production) PWA: - View the detailed breakdown and full score reports

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 85.27%. Comparing base (acb756e) to head (913cfbd).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8592      +/-   ##
==========================================
+ Coverage   85.18%   85.27%   +0.08%     
==========================================
  Files        1174     1175       +1     
  Lines       52490    52474      -16     
  Branches     2072     2074       +2     
==========================================
+ Hits        44716    44747      +31     
+ Misses       7267     7215      -52     
- Partials      507      512       +5     

Flag	Coverage Δ
backend	86.90% <ø> (ø)
migrations	43.17% <ø> (+0.03%)	⬆️
pui	69.36% <ø> (+0.18%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.