Switch to setuptools_scm for dynamic versioning

[Jepson2k]

Summary

Replaces the static version = "..." line in pyproject.toml with a dynamic = ["version"] declaration backed by setuptools_scm. The version is now read from the latest git tag reachable from HEAD at build time. Tagged commits get a clean version (v0.2.6 → "0.2.6"); commits past a tag get a dev suffix.

What changes

• pyproject.toml: add setuptools-scm>=8 to build-system.requires, replace version = "0.2.6" with dynamic = ["version"], add [tool.setuptools_scm] table. Removes the [tool.tbump] config block (tbump's only remaining role was tagging, which git tag already covers).
• .github/workflows/release.yml: deleted. Its only job was to sed the version into pyproject after a release was published and push the bump back to main, which is unnecessary once the tag is the source of truth.

Why

Fixes the issue we hit on v0.2.6 where the release-time auto-bump landed on main after the tag was placed, so pip install git+...@v0.2.6 resolved metadata of 0.2.5. With dynamic versioning the tag is the version — there's no separate line to keep in sync, no force-push of tags needed.

Industry context

Standard pattern for pip-installable Python libraries (pip, setuptools, pytest, numpy, scipy, scikit-learn, sphinx, click, attrs, pydantic).

Release flow after this

1. git tag -a vX.Y.Z -m "vX.Y.Z" on the commit you want to release
2. git push --tags
3. gh release create vX.Y.Z --notes "..."

pip install git+...@vX.Y.Z will report the matching version.

Follow-up

After this merges, the existing v0.2.6 tag still points at a pre-setuptools_scm commit, so it'll still install as 0.2.5. Either re-tag v0.2.6 at the post-merge commit, or cut a fresh v0.2.7 from the merged state.

Paired with sibling PRs on Jepson2k/waldoctl#1 and Jepson2k/pinokin#4.

---

PR description written by Claude on the author's behalf.