This tweaks Linux packages for Riot to SUID `chrome-sandbox` after install. This
is required as of Electron 5 for certain distros, such as Debian.
This change has also been provided to `electron-builder` upstream, so ideally
they'll include it in the future and this becomes redundant.
Fixes https://github.com/vector-im/riot-web/issues/10509
J. Ryan Stinnett