Update dependency NUnit to 4.5.0-alpha.0.18 (#1102)

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

Author: renovate[bot]

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

@@ -10,7 +10,7 @@
 
     <ItemGroup>
         <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.0.1" />
-        <PackageReference Include="NUnit" Version="4.5.0-alpha.0.17" />
+        <PackageReference Include="NUnit" Version="4.5.0-alpha.0.18" />
         <PackageReference Include="NUnit3TestAdapter" Version="5.2.0" />
         <PackageReference Include="NUnit.Analyzers" Version="4.11.2">
             <PrivateAssets>all</PrivateAssets>