[Luxon] fix ToRelativeUnit type (#36540)

There was a mistake in docs: https://github.com/moment/luxon/commit/83d350c46f3cf59567e574b121c39fdd4a6960da

types/luxon/index.d.ts

@@ -22,14 +22,14 @@ export interface ZoneOptions {
 }
 
 export type ToRelativeUnit =
-    | 'year'
-    | 'quarter'
-    | 'month'
-    | 'week'
-    | 'day'
-    | 'hour'
-    | 'minute'
-    | 'second';
+    | 'years'
+    | 'quarters'
+    | 'months'
+    | 'weeks'
+    | 'days'
+    | 'hours'
+    | 'minutes'
+    | 'seconds';
 
 export interface ToRelativeOptions {
     /** The DateTime to use as the basis to which this time is compared. Defaults to now. */

types/luxon/luxon-tests.ts

@@ -98,7 +98,7 @@ dt.toRelative({
     base: DateTime.local(),
     locale: 'fr',
     style: 'long',
-    unit: 'day',
+    unit: 'days',
     round: true,
     padding: 10,
     numberingSystem: 'bali',
@@ -108,7 +108,7 @@ dt.toRelative({
 dt.toRelativeCalendar({
     base: DateTime.local(),
     locale: 'fr',
-    unit: 'day',
+    unit: 'days',
     numberingSystem: 'bali',
 });