Drop support for py38 & uv chore upgrade

[teocns]

🎯 Purpose

Replace tox with uv for testing and dependency management to improve CI speed, simplify configuration, and modernize our tooling. Drop support for Python 3.8 (and lower) as it reached its EOL

🤔 Reasoning

1. Why UV?

   • 5-10x faster dependency resolution than pip
   • Better caching support in CI
   • Modern Python packaging features
   • Simpler configuration in pyproject.toml
   • Active development and community support

2. CI Testing:

• Workflow will automatically test against Python 3.9-3.13
• Coverage reports will be generated and uploaded to Codecov

📈 Performance Impact

• CI execution time expected to improve by 40-60%
• Dependency resolution time reduced by 5-10x
• Improved caching reduces subsequent run times

🔍 Additional Notes

• UV is maintained by the Ruff team, ensuring long-term support
• Migration is backward compatible - users can still use pip if preferred
• No changes to test code required

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Flag	Coverage Δ
unittests	37.53% <100.00%> (-14.82%)	⬇️

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

Files with missing lines	Coverage Δ
agentops/client.py	65.53% <100.00%> (ø)
agentops/helpers.py	56.04% <ø> (ø)

... and 12 files with indirect coverage changes

[teocns]

• Reverted some devin tests that are poorly implemented and misusing the async loop causing CI to timeout

• Reverted 82f9bb9 as support for <= 3.8 is dropped and it defeats the purpose of the commit

[the-praxs]

LGTM 🚀