Update dependency Microsoft.NET.Test.Sdk to v18

Author: renovate[bot]

Directory.Packages.props

@@ -61,7 +61,7 @@
         <PackageVersion Include="FakeItEasy" Version="8.3.0" />
 
         <PackageVersion Include="Shouldly" Version="4.3.0" />
-        <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
+        <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="18.0.0" />
         <PackageVersion Include="Moq" Version="4.20.72" />
         <PackageVersion Include="NSubstitute" Version="5.3.0" />
         <PackageVersion Include="Verify.FakeItEasy" Version="2.1.0" />