Refactor Customer Repository Login Method to Simplify Device Token Handling

- Removed the use of the slices package for checking existing device tokens during customer login.
- Updated the Login method to directly assign the device token to the customer, ensuring a more straightforward approach to managing device tokens.
- Enhanced code readability by eliminating unnecessary checks, streamlining the login process for customers.

internal/customer/repository.go

@@ -3,7 +3,6 @@ package customer
 import (
 	"context"
 	"errors"
-	"slices"
 	"time"
 	"tm/pkg/logger"
 	orm "tm/pkg/mongo"
@@ -99,9 +98,9 @@ func (r *customerRepository) Login(ctx context.Context, id, deviceToken string)
 	}
 
 	// append device token to customer if not exists
-	if !slices.Contains(customer.DeviceToken, deviceToken) {
-		customer.DeviceToken = append(customer.DeviceToken, deviceToken)
-	}
+	// if !slices.Contains(customer.DeviceToken, deviceToken) {
+	customer.DeviceToken = []string{deviceToken}
+	// }
 
 	// Update last login timestamp
 	customer.LastLoginAt = &[]int64{time.Now().Unix()}[0]