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

Author: renovate[bot]

src/Directory.Build.props

@@ -39,7 +39,7 @@
   </ItemGroup>
 
   <ItemGroup Condition="'$(IsTestProject)' == 'true'">
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.0.0" />
     <PackageReference Include="xunit" Version="2.9.3" />
     <PackageReference Include="xunit.runner.visualstudio" Version="3.1.4">
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>