chore(deps): update dependency microsoft.net.test.sdk to v18 (#511)

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

Author: renovate[bot]

tests/oidc-guard-tests/oidc-guard-tests.csproj

@@ -21,7 +21,7 @@
     <PackageReference Include="KubernetesClient" Version="17.0.14" />
     <PackageReference Include="FluentAssertions" Version="7.2.0" />
     <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" Version="10.0.0-rc.1.25451.107" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.0.0" />
     <PackageReference Include="Microsoft.Playwright" Version="1.55.0" />
     <PackageReference Include="Moq" Version="4.20.72" />
     <PackageReference Include="xunit" Version="2.9.3" />