I honestly don't know what to do for the best. Contentment still supports v8 (because it already worked and people are still actively using it, according to my telemetry stats), v9, v10 and v11. Which isn't fun to test against every Umbraco version. (I've recently dropped my v9 test site, as my telemetry stats tell me that active v9 usage has dropped to zero) and v10/v11 usage is pretty much equal. So I'm currently testing/supporting against v8/v10/v11. I think when v12 comes out, I'll drop v11 test site, but still support it, (as in keep any .NET 7 specific code in place, but not actively test it). With v13, it's too early to say anything concrete yet.