Revert "Use arrows instead of « and » in next previous article because they are more obvious"

This reverts commit 75847004df9ee4f3a0732088aac0dd9ac6196846.

@calfzhou said

> I prefer "«" (`&laquo;`) and "»" (`&raquo;`).

Also no other user has requested for it.

https://github.com/talha131/pelican-elegant/commit/75847004df9ee4f3a0732088aac0dd9ac6196846#commitcomment-5083703