Add missing OpenDbConnectionAsync overload

Author: mythz

src/ServiceStack.OrmLite/OrmLiteConnectionFactory.cs

@@ -230,6 +230,10 @@ public static IDbConnection Open(this IDbConnectionFactory connectionFactory)
         /// <summary>
         /// Alias for OpenDbConnectionAsync
         /// </summary>
+        public static Task<IDbConnection> OpenDbConnectionAsync(this IDbConnectionFactory connectionFactory, CancellationToken token = default)
+        {
+            return ((OrmLiteConnectionFactory)connectionFactory).OpenDbConnectionAsync(token);
+        }
         public static Task<IDbConnection> OpenAsync(this IDbConnectionFactory connectionFactory, CancellationToken token = default)
         {
             return ((OrmLiteConnectionFactory)connectionFactory).OpenDbConnectionAsync(token);