Code quality/project standards alignment

Similar to https://github.com/crytic/slither/issues/2096.

This is a meta-issue, intended to track sub-issues that will align tealer's codebase, development practices, etc. with the rest of our public tooling.

- [ ] Align `README.md` with our doc practices
- [ ] Modernize the Python codebase
- [ ] Switch to `pyproject.toml` (currently exists, but the build is in a separate `setup.py`)
- [ ] Use `pypa/build` for the build (sdist and wheel(s))
- [ ] Use `ruff`?
- [ ] Track Python dependency upgrades via `dependabot.yml`
- [ ] Add some kind of `QUICKSTART.md` or similar guide (broken out from the current `README.md`)

(This list is not intended to be exhaustive, and will be updated over time!)