npx instead of npm

Instead of installing ghost-cli, we prefer to simply use
npx run -p ghost-cli ghost

Moreover, it keeps the directory of the website empty of the ghost-cli node_module installation

💡
npx tool comes installed in the toolbox and image at Infomaniak, making it easier to run npm binaries without the hassle of installing / updating
npx | npm Docs
Run a command from a local or remote npm package