Make IStashboxContainer.Configure return IStashboxContainer

[schuettecarsten]

Please make Make IStashboxContainer.Configure return IStashboxContainer to allow code like this:

            // Stashbox
            builder.Host.UseStashbox(container => container
                .Configure(options => { })
                .Validate()
            );

[z4kn4fein]

Hi @schuettecarsten, I've released Stashbox v5.16.0 and v5.6.0 of the extension packages which allow the above usage. Could you please check that it works as you expected? Thanks!