Cancel and invalidate the URLSession task in the delegate callback test

The WebSocket task was created but never resumed or cancelled, which
aborts (SIGABRT) when URLSession deallocates it on CI.

Author: bgoncal

Tests/HAURLSessionWebSocketEngine.test.swift

@@ -118,7 +118,9 @@ internal class HAURLSessionWebSocketEngineTests: XCTestCase {
         engine.register(delegate: delegate)
 
         let session = URLSession(configuration: .ephemeral)
+        defer { session.invalidateAndCancel() }
         let task = try session.webSocketTask(with: XCTUnwrap(URL(string: "wss://example.com/api/websocket")))
+        task.cancel(with: .normalClosure, reason: nil)
 
         engine.urlSession(session, webSocketTask: task, didOpenWithProtocol: "chat")
         engine.urlSession(session, webSocketTask: task, didCloseWith: .goingAway, reason: Data("bye".utf8))