Update interval values in lemon-squeezy-webhook-handler

Changed the 'monthly' interval value to 'month' and the 'yearly' interval to 'year'. This change improves code consistency and alignment with the expected format for interval values.

packages/billing/lemon-squeezy/src/services/lemon-squeezy-webhook-handler.service.ts

@@ -435,13 +435,13 @@ function getSubscriptionIntervalType(renewsAt: string) {
 
   if (daysDifference <= 32) {
     return {
-      interval: 'monthly',
+      interval: 'month',
       intervalCount: 1,
     };
   }
 
   return {
-    interval: 'yearly',
+    interval: 'year',
     intervalCount: 12,
   };
 }