Improve Sphinx build by using SHA for version. Ignore SECURITY.md

[willingc]

This PR improves the Sphinx build's use of version. CI is throwing a few errors now:

Run nox -s docs-test
fatal: No names found, cannot describe anything.
nox > Running session docs-test
nox > Creating virtual environment (virtualenv) using python3 in .nox/docs-test
nox > python -m pip install -e .
nox > sphinx-build -b html --keep-going -E -a . _build/html
Running Sphinx v9.1.0
fatal: No names found, cannot describe anything.
loading translations [en]... done
making output directory... done

This fixes the fatal: No names found... error.

[agriyakhetarpal]

I can't seem to find any problems with this overall, so here's the green check :D