fix .net core build
fix .net core build

WasimAhmad/Serenity,rolembergfilho/Serenity,WasimAhmad/Serenity,volkanceylan/Serenity,volkanceylan/Serenity,volkanceylan/Serenity,rolembergfilho/Serenity,volkanceylan/Serenity,WasimAhmad/Serenity,rolembergfilho/Serenity,WasimAhmad/Serenity,rolembergfilho/Serenity,volkanceylan/Serenity,rolembergfilho/Serenity,WasimAhmad/Serenity