Merge pull request #716 from Quick/8.x-fix-spm-build

[8.x] Fix hanging toEventually when build with swift package manager (SPM)

Author: ikesyo

Sources/Nimble/Utils/Await.swift

@@ -98,7 +98,7 @@ internal enum AwaitResult<T> {
 
 /// Holds the resulting value from an asynchronous expectation.
 /// This class is thread-safe at receiving an "response" to this promise.
-internal class AwaitPromise<T> {
+internal final class AwaitPromise<T> {
     private(set) internal var asyncResult: AwaitResult<T> = .incomplete
     private var signal: DispatchSemaphore