Update dependency Microsoft.NET.Test.Sdk to v18

Author: renovate[bot]

Directory.Packages.props

@@ -7,7 +7,7 @@
     <PackageVersion Include="Altinn.App.Core" Version="8.6.5" />
     <PackageVersion Include="coverlet.collector" Version="6.0.4" />
     <PackageVersion Include="CSharpier.MsBuild" Version="1.1.2" />
-    <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
+    <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="18.0.1" />
     <PackageVersion Include="Microsoft.NETFramework.ReferenceAssemblies" Version="1.0.3" />
     <PackageVersion Include="Microsoft.SourceLink.GitHub" Version="8.0.0" />
     <PackageVersion Include="Mime-Detective" Version="25.8.1" />