CI: update to modern vanagon syntax and be verbose

the `build` command is deprecated:

https://github.com/OpenVoxProject/vanagon/blob/main/bin/build

Signed-off-by: Tim Meusel <tim@bastelfreak.de>

Author: bastelfreak

tasks/build.rake

@@ -19,7 +19,7 @@ namespace :vox do
     end
 
     engine = platform =~ /^(macos|windows)-/ ? 'local' : 'docker'
-    cmd = "bundle exec build #{project} #{platform} --engine #{engine}"
+    cmd = "bundle exec vanagon build #{project} #{platform} --engine #{engine} --verbose"
 
     FileUtils.rm_rf('C:/ProgramFiles64Folder/') if platform =~ /^windows-/