sdist tests should test on lowercased package name

[IAlibay]

Due to some changes in pypi-land, packages are now being normalized to lowercase (todo: add in the relevant docs here when I get a chance).

This means that when testing if a package will form an sdist tarball, we should make sure that the name of the tarball is lowercased, i.e.

cookiecutter-mdakit/{{cookiecutter.repo_name}}/.github/workflows/{{cookiecutter._ci_name}}.yaml

Line 177 in a1a9201

DISTRIBUTION=$(ls -t1 dist/{{ cookiecutter.repo_name }}-*.tar.gz | head -n 1)