Try 2019 image

FlorianRappl · FlorianRappl · commit 06f0a68ca45d · 2019-10-31T23:52:37.000+01:00
diff --git a/appveyor.yml b/appveyor.yml
@@ -4,7 +4,7 @@ branches:
   - master
   - dev
 skip_tags: true
-image: Visual Studio 2015
+image: Visual Studio 2019
 configuration: Release
 platform: Any CPU
 build_script:
