actions-rs/toolchain is archived. Rust is currently installed on GitHub
actions runners. So the action was replaced by using rustup to install a
minimal profile.

build and test staged were added.

Updated all steps to the latest version

The format is so simple that a custom parser would be much safer and
faster than using regex. The original also should have used `^` instead
of `\n`.

This is one of the steps towards removing regex as a dependecy for this
project and replacing it with parsers for the specific file formats.

Add support for a different location of `/etc/login.defs` file and
override the assumed defaults if the file is not present.