Refactor: use pyproject.toml for project metadata, requirements, build settings

[thekaveman]

• there were no library dependencies / top-level requirements.txt to deal with
• Removes setup.py, setup.cfg, and each of the dev-time requirements.txt (devcontainer and tests)
• Moves all project metadata, requirements, etc. to pyproject.toml
• Update devcontainer and GitHub Actions package installation using new [dev] "extras" target under [project.optional-dependencies]

Also a few small fixes

• Updated syntax for compose.yml and devcontainer.json
• Updated development environment from Python 3.10 --> Python 3.11