Remove margin-bottom for list items

[ulinaaron]

This is an oversight that just needs to be removed from the next build. Currently all list items have a bottom margin. If anything they just need natural line spacing going forward.

https://github.com/sitetent/tentcss/blob/b563e72e3c85807188d930a816ca520eee3f07a3/src/04_elements/_lists.scss#L21

 margin-bottom: map-get($spaces, xxxs);