uMatrix/dist/firefox/updates.json

{
 "addons": {
  "uMatrix@raymondhill.net": {
   "updates": [
    {
     "version": "1.4.1.2",
     "browser_specific_settings": { "gecko": { "strict_min_version": "56" } },
     "update_info_url": "https://github.com/gorhill/uMatrix/releases/tag/1.4.1b2",
     "update_link": "https://github.com/gorhill/uMatrix/releases/download/1.4.1b2/uMatrix_1.4.1b2.firefox.signed.xpi"
    }
   ]
  }
 }
}