Add timeout to RequestBagTests.testCancelFailsTaskAfterRequestIsSent test (#699)

We have seen that the `RequestBagTests.testCancelFailsTaskAfterRequestIsSent` can timeout the CI. To better understand where it fails we can add a timeout that will throw with a timeout error and fail the error check below it. This will make will allow us in the future to better analyse the failure and will no longer timeout the CI.

Author: dnadoba

Tests/AsyncHTTPClientTests/RequestBagTests.swift

@@ -345,7 +345,7 @@ final class RequestBagTests: XCTestCase {
         bag.fail(HTTPClientError.cancelled)
         XCTAssertTrue(executor.isCancelled, "The request bag, should call cancel immediately on the executor")
 
-        XCTAssertThrowsError(try bag.task.futureResult.wait()) {
+        XCTAssertThrowsError(try bag.task.futureResult.timeout(after: .seconds(10)).wait()) {
             XCTAssertEqual($0 as? HTTPClientError, .cancelled)
         }
     }