Go back to AppVeyor's latest Visual Studio 2019 image

Author: Jericho

appveyor.yml

@@ -24,7 +24,7 @@ cache:
   - tools -> build.cake, tools\packages.config
 
 # Environment configuration
-image: Previous Visual Studio 2019
+image: Visual Studio 2019
 
 #---------------------------------#
 #  Skip builds for doc changes    #