Exclude the dummy project from coverage

Author: Tyrrrz

CliFx.Tests.Dummy/Program.cs

@@ -1,8 +1,11 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.IO;
 using System.Reflection;
 using System.Threading.Tasks;
 
+[assembly: ExcludeFromCodeCoverage]
+
 namespace CliFx.Tests.Dummy;
 
 // This dummy application is used in tests where an external process is required