Upgrade ubuntu

needed to run node v18 - https://www.appveyor.com/docs/linux-images-software/

https://help.appveyor.com/discussions/problems/33559-please-add-node-v18-x86-version-to-the-windows-build-vms

Author: Almenon

appveyor.yml

@@ -6,7 +6,7 @@ branches:
 
 image:
 - Visual Studio 2017
-- Ubuntu
+- Ubuntu2004
 
 environment:
   matrix: