.net core sdk 3.1 (#1388)

Author: bergmeister

README.md

@@ -105,7 +105,7 @@ Note: the PSScriptAnalyzer Chocolatey package is provided and supported by the c
 
 #### Requirements
 
-* [.NET Core 2.2.402 SDK](https://www.microsoft.com/net/download/dotnet-core/2.2#sdk-2.2.402) or newer patch release
+* [.NET Core 3.1.100 SDK](https://www.microsoft.com/net/download/dotnet-core/3.1#sdk-3.1.100) or newer patch release
 * [PlatyPS 0.13.0 or greater](https://github.com/PowerShell/platyPS/releases)
 * Optionally but recommended for development: [Visual Studio 2017/2019](https://www.visualstudio.com/downloads/)
 

global.json

@@ -1,5 +1,5 @@
 {
     "sdk": {
-        "version": "2.2.402"
+        "version": "3.1.100"
     }
 }