feat: pull latest-20 image in herokuish package
feat: pull latest-20 image in herokuish package

Also avoid pruning the freshly pulled images
gliderlabs/herokuish,gliderlabs/herokuish,gliderlabs/herokuish,gliderlabs/herokuish,gliderlabs/herokuish,gliderlabs/herokuish,gliderlabs/herokuish,gliderlabs/herokuish