ci: print the appveyor agent version at the start of the build
ci: print the appveyor agent version at the start of the build

aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,graydon/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust