chore(deps): update dependency microsoft.net.test.sdk to v18

Author: renovate[bot]

GodotEnv.Tests/Chickensoft.GodotEnv.Tests.csproj

@@ -11,7 +11,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.0.0" />
     <PackageReference Include="System.IO.Abstractions.TestingHelpers" Version="22.0.16" />
     <PackageReference Include="xunit" Version="2.9.3" />
     <PackageReference Include="xunit.runner.visualstudio" Version="3.1.5">