install dotnet in CI based on global.json (#589)

* install dotnet in CI based on global.json

* Update global.json

Author: SimonCropp

appveyor.yml

@@ -18,7 +18,11 @@ init:
               Set-AppveyorBuildVariable -Name "IsPreRelease" -Value False
             }
 
-build_script: build.cmd ci
+build_script:
+- pwsh: |
+    Invoke-WebRequest "https://dot.net/v1/dotnet-install.ps1" -OutFile "./dotnet-install.ps1"
+    ./dotnet-install.ps1 -JSonFile global.json -Architecture x64 -InstallDir 'C:\Program Files\dotnet'
+- build.cmd ci
 
 test: off
 

global.json

@@ -1,6 +1,6 @@
 {
   "sdk": {
-    "version": "9.0.101",
+    "version": "9.0.200",
     "allowPrerelease": true,
     "rollForward": "latestFeature"
   }