Fixing pagination disabled border using wrong variable (#863)

Signed-off-by: hong <hong@aftership.net>

sass/components/pagination.sass

@@ -68,7 +68,7 @@ $pagination-shadow-inset: inset 0 1px 2px rgba($black, 0.2)
     box-shadow: $pagination-shadow-inset
   &[disabled]
     background-color: $pagination-disabled-background
-    border-color: $pagination-border
+    border-color: $pagination-disabled-border
     box-shadow: none
     color: $pagination-disabled
     opacity: 0.5