Replace combine imports with Observation

Author: joshheald

WooCommerce/Classes/POS/Controllers/PointOfSaleOrderController.swift

@@ -1,5 +1,5 @@
 import Foundation
-import Combine
+import Observation
 import protocol Yosemite.StoresManager
 import protocol Yosemite.POSOrderServiceProtocol
 import protocol Yosemite.POSReceiptServiceProtocol

WooCommerce/WooCommerceTests/POS/Controllers/PointOfSaleOrderControllerTests.swift

@@ -1,5 +1,5 @@
 import Testing
-import Combine
+import Observation
 import Foundation
 
 @testable import WooCommerce