Resolve some build errors.

Author: danielrbrowne

Sources/Extensions/PusherWebsocketDelegate.swift

@@ -1,3 +1,4 @@
+import Foundation
 import Network
 
 extension PusherConnection: WebSocketConnectionDelegate {

Sources/Models/WebSocket.swift

@@ -1,3 +1,4 @@
+import Foundation
 import Network
 
 /// Manages a websocket connection to a given server which can accept such connections.

Sources/Protocols/WebSocketConnection.swift

@@ -1,3 +1,4 @@
+import Foundation
 import Network
 
 /// Defines a websocket connection.

Tests/Helpers/Mocks.swift

@@ -1,4 +1,5 @@
 import Foundation
+import Network
 
 #if WITH_ENCRYPTION
     @testable import PusherSwiftWithEncryption
@@ -46,7 +47,7 @@ open class MockWebSocket: WebSocket {
         )
     }
 
-    open override func disconnect(closeCode: Int = URLSessionWebSocketTask.CloseCode.normalClosure.rawValue) {
+    open override func disconnect(closeCode: NWProtocolWebSocket.CloseCode = .protocolCode(.normalClosure)) {
         _ = stubber.stub(
             functionName: "disconnect",
             args: nil,