Upgrade CI image

Author: hedgehog1029

.github/workflows/main.yml

@@ -7,7 +7,7 @@ on:
 
 jobs:
   build:
-    runs-on: windows-2019
+    runs-on: windows-latest
     steps:
       - uses: actions/checkout@v2
       - uses: NuGet/setup-nuget@v1.0.5