Update dependency Microsoft.NET.Test.Sdk to v18 (#1076)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

docs/snippets/Snippets.NUnit/Snippets.NUnit.csproj

@@ -9,7 +9,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.0.0" />
     <PackageReference Include="NUnit" Version="4.4.0" />
     <PackageReference Include="NUnit3TestAdapter" Version="5.1.0" />
     <PackageReference Include="NUnit.Analyzers" Version="4.10.0">

docs/snippets/Snippets.NUnitLite/Snippets.NUnitLite.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="NUnit" Version="4.4.0" />
     <PackageReference Include="NUnit3TestAdapter" Version="5.1.0" />
     <PackageReference Include="NUnit.Analyzers" Version="4.10.0">