<hr> hard to see in darkly theme.

[dessalines]

[RayBB]

Looks like we'd want to make the change here: https://github.com/LemmyNet/lemmy-ui/blob/105bbe44609648c188eb8d1de28f86f7b21f9bd1/src/shared/components/post/post-listings.tsx#L46

By adding some of the related hr classes from boostrap: https://getbootstrap.com/docs/5.2/content/reboot/#horizontal-rules