Fixed: Settings fail to save for some auth setups

src/Sonarr.Api.V3/Config/HostConfigController.cs

@@ -42,8 +42,10 @@ namespace Sonarr.Api.V3.Config
             SharedValidator.RuleFor(c => c.UrlBase).ValidUrlBase();
             SharedValidator.RuleFor(c => c.InstanceName).StartsOrEndsWithSonarr();
 
-            SharedValidator.RuleFor(c => c.Username).NotEmpty().When(c => c.AuthenticationMethod != AuthenticationType.None);
-            SharedValidator.RuleFor(c => c.Password).NotEmpty().When(c => c.AuthenticationMethod != AuthenticationType.None);
+            SharedValidator.RuleFor(c => c.Username).NotEmpty().When(c => c.AuthenticationMethod == AuthenticationType.Basic ||
+                                                                          c.AuthenticationMethod == AuthenticationType.Forms);
+            SharedValidator.RuleFor(c => c.Password).NotEmpty().When(c => c.AuthenticationMethod == AuthenticationType.Basic ||
+                                                                          c.AuthenticationMethod == AuthenticationType.Forms);
 
             SharedValidator.RuleFor(c => c.SslPort).ValidPort().When(c => c.EnableSsl);
             SharedValidator.RuleFor(c => c.SslPort).NotEqual(c => c.Port).When(c => c.EnableSsl);