Notify user when new version is available

[fonsp]

By fetching Project.toml from jsDelivr.

[fonsp]

Can be done in the frontend like this:

fetch("https://api.github.com/repos/fonsp/Pluto.jl/releases", {
            method: 'GET',
            cache: 'no-cache',
            headers: {
                'Content-Type': 'application/json',
            },
            redirect: 'follow',
            referrerPolicy: 'no-referrer',
        }).then((response) => {
            return response.json()
        }).then((response) => {
            console.log(response[0].tag_name)
        }).catch(console.error)

prints

v0.5.1

(or whatever the latest version is)

[fonsp]

Could be improved by directly running import Pkg; Pkg.update("Pluto"), but only if the user can see the installation progress/logs.