serialize as str when field is UUID type

[juggler31]

Il y avait des warnings lors de la sérialization d'un objet UUID.

[coveralls]

coverage: 78.383% (+0.7%) from 77.647%
when pulling 2376b88 on serialize_uuid
into 6395159 on master.

[Copilot]

Pull request overview

This PR addresses UUID serialization warnings by serializing uuid.UUID values as strings, and updates CI to adjust the Python/Django test matrix and GitHub Actions versions.

Changes:

• Serialize uuid.UUID fields as str in _serialize_field to avoid JSON serialization warnings.
• Remove Python 3.7 from the GitHub Actions matrix and update Actions used in the workflow.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
tracking_fields/tracking.py	Adds explicit UUID handling in field serialization.
.github/workflows/python-app.yml	Updates Python version matrix and bumps GitHub Actions versions.

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[Copilot]

The matrix exclude list was previously excluding Python 3.7 for Django 4.x (unsupported). Now that 3.7 is removed from the matrix, these entries were changed to exclude Python 3.8 instead, which is a supported combination for Django 4.0/4.1/4.2 and is also covered in tox. This unintentionally drops CI coverage for Python 3.8 on Django 4.x; remove these exclude items (or adjust them to only exclude truly unsupported pairs, e.g. Django 4.0 with Python 3.11).

[Gagaro]

Il faudrait mettre le README à jour au passage pour changer la version minimal de Django et enlever la mention de django-cuser + ajouter un passage sur le middleware à rajouter dans les settings pour avoir le user.