fix: replace border-gray-300 with a themable colour (#664)

Co-authored-by: Aman Harwara <amanharwara@protonmail.com>

app/assets/javascripts/components/shared/HorizontalSeparator.tsx

@@ -6,5 +6,5 @@ type Props = {
 export const HorizontalSeparator: FunctionalComponent<Props> = ({
   classes = ''
 }) => {
-  return <hr className={`h-1px w-full bg-border no-border ${classes}`} />;
+  return <hr className={`h-1px w-full bg-neutral no-border ${classes}`} />;
 };

app/assets/javascripts/components/shared/ModalDialog.tsx

@@ -44,7 +44,7 @@ export const ModalDialogLabel: FunctionComponent<{
         Close
       </div>
     </div>
-    <hr className="h-1px bg-border no-border m-0" />
+    <hr className="h-1px bg-neutral no-border m-0" />
   </AlertDialogLabel>
 );