Use dynamic versioning (#155)

[nkoep]

Randomly spotted this open issue and figured I'd have a go at it. Hope there are no objections to using setuptools-scm.

[lucianopaz]

Thanks @nkoep. I have to say that I'm strongly against setuptools-scm. I wanted to use it to get the version automatically from git tags but its main problem is that it assumes that the files you want to package are all the files that are tracked by version control. This includes:

• .github/workflow
• docs
• causalpy/tests
• All the files in the root folder like codecov, readthedocs, .gitignore, etc

In practice, setuptools-scm completely ignores the arguments of the [tool.setuptools.packages.find] section of pyproject.toml and does whatever it wants. From reading a bit of issues, this was documented back in 2017 and flagged as wont-fix because they say it's setuptools fault to opt to include all files from git. Until there is a sane solution to this problem, I will remain strongly against setuptools-scm.

[drbenvincent]

Definitely appreciate the effort @nkoep, but as @lucianopaz points out, setuptools-scm looks to have some problems, so I'll close this PR for now. Don't let that put you off making any other contributions if you like :)