Add enum for weekday and validate that closing time is after opening time

Author: AnnaZiafar

src/main/java/org/example/entities/OpeningHours.java

@@ -11,7 +11,7 @@ public class OpeningHours {
     @GeneratedValue(strategy = GenerationType.IDENTITY)
     private Long id;
 
-    @Enumerated(EnumType.ORDINAL)
+    @Enumerated(EnumType.STRING)
     private Weekday weekday;
 
     private LocalTime openingTime;