Bugfix/base url in docker (#1901)

* fixed: BaseUrl option is not supported in Docker

- discussion in #1824, the checks should not have been added in the first place

* changed: contributors require .NET 7.0+ in order to build

API/Startup.cs

@@ -391,7 +391,6 @@ public class Startup
     {
         try
         {
-            if (new OsInfo(Array.Empty<IOsVersionAdapter>()).IsDocker) return;
             var htmlDoc = new HtmlDocument();
             var indexHtmlPath = Path.Combine(Directory.GetCurrentDirectory(), "wwwroot", "index.html");
             htmlDoc.Load(indexHtmlPath);