Made builder tests run sequentially

tests/PixiEditor.Extensions.Tests/LayoutBuilderElementsTests.cs

@@ -3,6 +3,7 @@ using PixiEditor.Extensions.FlyUI.Elements;
 
 namespace PixiEditor.Extensions.Test;
 
+[Collection("LayoutBuilderTests")]
 public class LayoutBuilderElementsTests
 {
     [Fact]

tests/PixiEditor.Extensions.Tests/LayoutBuilderTests.cs

@@ -6,6 +6,7 @@ using Button = PixiEditor.Extensions.FlyUI.Elements.Button;
 
 namespace PixiEditor.Extensions.Test;
 
+[Collection("LayoutBuilderTests")]
 public class LayoutBuilderTests
 {
     [Fact]