RFC: Refactor dev dependencies lists and remove tox

[zliang-akamai]

Our tox config is outdated (containing EOL Python versions, lacking newer Python versions), and it's unnecessary to run the unit tests as we already directly use pytest in make test-unit.

Removal of tox can unify things so we don't have to define unit tests dependencies in two places (pyproject.toml and tox.ini), and we will get a more consistent behavior between CI and local make test-unit because they both run pytest directly.

[Copilot]

🟢 Approval recommended

The dependency/execution changes are internally consistent across pyproject.toml, README, and CI, and tox references appear fully removed from the repo’s workflow.

Pull request overview

This PR removes the repository’s tox-based test runner and consolidates test/dev dependency management into pyproject.toml extras, aligning local workflows with CI by running unit tests directly via pytest through make test-unit.

Changes:

• Removed tox.ini and updated documentation to run unit tests via pip install ".[unit-test]" + make test-unit.
• Refactored pyproject.toml optional dependency groups into test-shared, unit-test, int-test, lint, doc, and dev.
• Updated GitHub Actions CI to install the new unit-test extra and run make test-unit instead of invoking tox.

File summaries

File	Description
tox.ini	Removes tox configuration entirely.
README.rst	Updates contributor test instructions to use .[unit-test] and make test-unit.
pyproject.toml	Reorganizes optional dependency extras to avoid duplicating test deps across tools.
AGENTS.md	Removes tox.ini-related guidance now that tox is gone.
.github/workflows/ci.yml	Switches CI test execution from tox to make test-unit with the new extra.

Review details

• Files reviewed: 5/5 changed files
• Comments generated: 0
• Review effort level: Lite

---

💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.