feat: add Python 3.12 support and drop Python 3.8

[hiteshkava]

Description

Cherry-picked from openedx/xqueue-watcher#120 ("chore: drop Python 3.11 support"), following the same pattern used for the xqueue Python 3.12 upgrade (edx/xqueue#3). Our fork was sitting exactly at the state right before upstream openedx#120 (CI matrix ['3.11', '3.12'], common_constraints.txt matching pre-openedx#120 exactly), so the cherry-pick applied cleanly.

Changes

File	Change	Why
.github/workflows/ci.yml	python-version: ['3.11', '3.12'] → ['3.12']	Drop Python 3.11, test only 3.12
requirements/common_constraints.txt	Django<5.0 → Django<6.0; removed pip<24.3 and urllib3<2.3.0 pins	Both upstream edx-lint issues these pins referenced are resolved; matches openedx#120
requirements/*.txt (base, ci, pip, pip_tools, production, test)	Fully regenerated with Python 3.12 (make upgrade)	Per the documented org-wide process
setup.py	version='0.4' → '1.0.0'	Dropping Python support is a breaking change (matches upstream's major version bump)

Out of scope

The repo's own Dockerfile (still Ubuntu 16.04 Xenial + Python 2) is untouched — production deploys via the AMI/Ansible xqwatcher GoCD pipeline, not Docker, and this Dockerfile appears unused.

Testing

• pytest: 24/25 pass. The one failure (test_jailed_grader.py::test_correct) is a pre-existing environment gap (codejail/apparmor sandbox not configured in this dev container) — reproduced identically on Python 3.11 with the original, pre-upgrade requirements, confirming it's not a Python 3.12 regression.
• All core modules (client, grader, jailedgrader, manager, settings) import cleanly under Python 3.12.3, and the CLI entrypoint (python -m xqueue_watcher -d <config_root>) starts up without error.
• Checked jailedgrader.py's use of SourceFileLoader.load_module() — triggers a DeprecationWarning under 3.12 but still functions; not a current blocker, worth a follow-up to migrate to exec_module().

Related

• Companion configuration role update: feat: upgrade xqwatcher to Python 3.12 configuration#387 — adds the Jammy/Python 3.12 install task this role was previously missing entirely
• Companion edx-internal AMI pipeline bump: https://github.com/edx/edx-internal/pull/14969 — gocd/manually-created-pipelines/xqwatcher.yaml Ubuntu 20.04 → 22.04, plus the per-course PYTHON_EXECUTABLE/numpy pin updates
• Open question, not resolved by this PR: two per-course grader sandboxes (MITx-7.QBWx, MITx-6.00x) still need their own verification against MIT's private grader repos — see edx-internal#14969 for the numpy/Python-version details on that