Fixed open api enum schema filter not setting type

By not setting the type and format, it would remain integer is this case, which would result in an invalid specification as the enum members are strings.

src/Umbraco.Cms.Api.Common/OpenApi/EnumSchemaFilter.cs

@@ -12,6 +12,8 @@ public class EnumSchemaFilter : ISchemaFilter
     {
         if (context.Type.IsEnum)
         {
+            model.Type = "string";
+            model.Format = null;
             model.Enum.Clear();
             foreach (var name in Enum.GetNames(context.Type))
             {