[FIX] Ensure modern setuptools for gevent installs with --no-build-isolation (#93)

[brinkflew]

Old setuptools (58–59) pins break pip install --no-build-isolation for gevent (and other sdists) with current pip: PEP 517 cannot load setuptools.build_meta reliably.

• Raise the floor to setuptools>=69 in odev/static/requirements.txt for Python >= 3.8.
• Bootstrap new Odoo venvs with setuptools>=69.0.0; before installing gevent, upgrade setuptools and wheel so existing venvs recover without manual steps.

Add unit tests for the static requirements policy and prepare_venv call order.

Linked Issues

Link the issues that this PR solves, if any:

• Cannot import 'setuptools.build_meta' when installing gevent on Ubuntu 24.04 #93

Compliance

• I have read the contribution guide
• I made sure the documentation is up-to-date both in doctrings and the docs directory
• I have added or modified unit tests where necessary
• I have added new libraries to the requirements.txt file, if any
• I have incremented the version number according the versioning guide
• The PR contains my changes only and no other external commit