docs build increments the version prematurely

Describe the bug

setuptools_scm increments the patch/bugfix semver version if the git repo is "dirty" (docs here)

This is an issue in our docs building as of v1.4.0 (when we switched to setuptools_scm), since something about our docs build is triggering this patch version increment:

https://app.readthedocs.org/projects/openfe/builds/27970219/

This only affects our installation docs, so as a short-term fix we can just include the major and minor versions (e.g. 1.4).

Longer-term, I'd like to build our docs such that a fresh version tag is not detected as "dirty". Alternatively, we can use a custom versioning scheme as a long-term solution.

Start by inspecting ReadTheDocs build 27970219 and the installation documentation affected by the version change, then trace how setuptools_scm sees the repository during the docs build. Compare the short-term major/minor-only requirement with the longer-term clean-tag or custom-versioning alternatives; done means the docs no longer show the premature patch increment.