fix: src/Umbraco.Community.SimpleTrees.TestSite/Umbraco.Community.SimpleTrees.TestSite.csproj to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-DOTNET-UMBRACOCMSAPIDELIVERY-11334729

Author: snyk-bot

src/Umbraco.Community.SimpleTrees.TestSite/Umbraco.Community.SimpleTrees.TestSite.csproj

@@ -7,7 +7,7 @@
 
 	<ItemGroup>
 		<PackageReference Include="NuGet.Protocol" Version="6.14.0" />
-		<PackageReference Include="Umbraco.Cms" Version="16.0.0"/>
+		<PackageReference Include="Umbraco.Cms" Version="16.1.1"/>
 		<PackageReference Include="uSync" Version="16.0.0"/>
 	</ItemGroup>