use kotlin serialization

src/Application.kt

@@ -5,11 +5,11 @@ import io.ktor.application.*
 import io.ktor.response.*
 import io.ktor.routing.*
 import io.ktor.http.*
-import io.ktor.gson.*
 import io.ktor.features.*
 import org.apache.http.HttpException
 import com.kmalbz.database.DatabaseFactory
 import com.kmalbz.database.dao.SampleObjects
+import io.ktor.serialization.*
 import io.ktor.util.*
 import org.jetbrains.exposed.sql.SchemaUtils
 import org.jetbrains.exposed.sql.transactions.transaction
@@ -21,8 +21,7 @@ fun main(args: Array<String>): Unit = io.ktor.server.netty.EngineMain.main(args)
 @Suppress("unused") // Referenced in application.conf
 fun Application.module() {
     install(ContentNegotiation) {
-        gson {
-        }
+        json()
     }
 
     install(Koin) {