optimize code

src/main/java/com/faf223/expensetrackerfaf/service/ExpenseService.java

@@ -10,9 +10,13 @@ import java.util.List;
 @Service
 public class ExpenseService {
 
-    @Autowired
     private ExpenseRepository expenseRepository;
 
+    @Autowired
+    public ExpenseService(ExpenseRepository expenseRepository) {
+        this.expenseRepository = expenseRepository;
+    }
+
     public List<Expense> getExpensesByUserId(String userUuid) {
         return expenseRepository.findByUserUserUuid(userUuid);
     }