Update dependency Microsoft.AspNetCore.TestHost to v6.0.8

Author: renovate[bot]

Diff for: src/NHibernate.Test/NHibernate.Test.csproj

@@ -77,7 +77,7 @@
     <PackageReference Include="Oracle.ManagedDataAccess" Version="21.6.1" />
   </ItemGroup>
   <ItemGroup Condition="'$(TargetFramework)'=='net6.0'">
-    <PackageReference Include="Microsoft.AspNetCore.TestHost" Version="6.0.1" />
+    <PackageReference Include="Microsoft.AspNetCore.TestHost" Version="6.0.8" />
     <PackageReference Include="System.CodeDom" Version="4.7.0" />
     <PackageReference Include="System.Data.SqlClient" Version="4.8.3" />
     <PackageReference Include="System.Data.OracleClient" Version="1.0.8" />