Use git repo data (latest tag, current commit hash, etc) for building a
version number according PEP 440.

- Can be installed & configured through both setup.py and PEP 518's
pyproject.toml

- Does not require to change source code of the project

- Tag-, file-, and callback-based versioning schemas are supported

- Templates for tag, dev and dirty versions are separated

- Templates support a lot of substitutions including git and environment
information

- Well-documented
