Update VS image for AppVeyor (#5101)

stevejgordon · github-actions[bot] · commit 0c0218a1ee28 · 2020-11-19T16:00:34.000Z
diff --git a/appveyor.yml b/appveyor.yml
@@ -1,6 +1,6 @@
 version: 1.0.{build}
 image:
-    - Visual Studio 2017
+    - Visual Studio 2019
 test: off
 environment:
     DOTNET_CLI_TELEMETRY_OPTOUT: true
