update to .NET Core 3.1

Author: damienbod

README.md

@@ -1,9 +1,11 @@
-# ASP.NET Core 3.0 MVC file upload / download with MS SQL Server FileTable
+# ASP.NET Core 3.1 MVC file upload / download with MS SQL Server FileTable
 
 https://damienbod.com/2015/12/05/asp-net-5-mvc-6-file-upload-with-ms-sql-server-filetable/
 
 ## History 
 
+2019-12-21 Updated to .NET Core 3.1
+
 2019-10-05 Updated to .NET Core 3.0
 
 2019-06-16 Updated to .NET Core packages, npm packages, in process hosting