Enable parallel tests

Author: xPaw

SteamKit2/Tests/DebugLogFacts.cs

@@ -27,6 +27,7 @@ public override void After( System.Reflection.MethodInfo methodUnderTest )
         }
     }
 
+    [CollectionDefinition( nameof( DebugLogFacts ), DisableParallelization = true )]
     public class DebugLogFacts
     {
         [Fact, DebugLogSetupTeardown]

SteamKit2/Tests/Properties/AssemblyInfo.cs

@@ -1,6 +1,5 @@
 using System.Reflection;
 using System.Runtime.InteropServices;
-using Xunit;
 
 // General Information about an assembly is controlled through the following 
 // set of attributes. Change these attribute values to modify the information
@@ -21,5 +20,3 @@
 
 // The following GUID is for the ID of the typelib if this project is exposed to COM
 [assembly: Guid("dcef76fb-0139-4e17-a8cd-973a7d9bd856")]
-
-[assembly: CollectionBehavior(DisableTestParallelization = true)]