Update Microsoft.NET.Test.Sdk package version to 18.0.0

Author: niemyjski

tests/Directory.Build.props

@@ -6,7 +6,7 @@
     <NoWarn>$(NoWarn);CS1591;NU1701</NoWarn>
   </PropertyGroup>
   <ItemGroup>
-    <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="3.1.5" />