Fix build errors for non-Chickensoft packages (#97)

Fully qualify Chickensoft.GoDotTest in a using statement, so that
packages created with this tool that are not in the Chickensoft
namespace will build without errors.

Chickensoft.GodotPackage.Tests/test/Tests.cs

@@ -2,7 +2,7 @@ namespace Chickensoft.GodotPackage.Tests;
 
 using System.Reflection;
 using Godot;
-using GoDotTest;
+using Chickensoft.GoDotTest;
 
 public partial class Tests : Node2D {
   public override void _Ready()