fix flaky test

Author: hjgraca

libraries/tests/AWS.Lambda.Powertools.Common.Tests/ConsoleWrapperTests.cs

@@ -31,6 +31,7 @@ public void Error_Should_Write_To_Error_Console()
 
         // Act
         consoleWrapper.Error("error message");
+        writer.Flush();
 
         // Assert
         Assert.Equal($"error message{Environment.NewLine}", writer.ToString());