Update Windows Server and Visual Studio versions to 2019

Author: JohnTitor

ci/azure.yml

@@ -102,7 +102,7 @@ jobs:
 
   - job: Windows
     pool:
-      vmImage: vs2017-win2016
+      vmImage: windows-2019
     steps:
       - template: azure-install-rust.yml
       - bash: LIBC_CI=1 sh ./ci/run.sh $TARGET