Fix whole YieldAsyncTests

Author: Meyn

UnitTest/ParallelRequestHandlerTests.cs

@@ -223,7 +223,7 @@ public async Task RunRequests_WithMultipleRequests_ShouldExecuteAll()
         #region State Events Tests
 
         [Test]
-        public void StateChanged_WhenStateChanges_ShouldFireEvent()
+        public async Task StateChanged_WhenStateChanges_ShouldFireEvent()
         {
             // Arrange
             List<RequestState> stateChanges = [];
@@ -232,6 +232,8 @@ public void StateChanged_WhenStateChanges_ShouldFireEvent()
             // Act
             _handler.Pause();
 
+            await Task.Delay(100);
+
             // Assert
             stateChanges.Should().NotBeEmpty();
             stateChanges.Should().Contain(RequestState.Paused);