Update wpf.oidc.client.authorization-code.csproj

Author: linianhui

1-src/wpf.oidc.client.authorization-code/wpf.oidc.client.authorization-code.csproj

@@ -1,8 +1,8 @@
-<Project Sdk="Microsoft.NET.Sdk.WindowsDesktop">
+<Project Sdk="Microsoft.NET.Sdk.WindowsDesktop">
 
   <PropertyGroup>
     <OutputType>WinExe</OutputType>
-    <TargetFramework>net5.0-windows</TargetFramework>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
     <RootNamespace>WPFClient</RootNamespace>
     <UseWPF>true</UseWPF>
     <StartupObject>WPFClient.App</StartupObject>