Fix install issues in Debian 11 & update electron-builder

New versions of Electron-Builder use new versions of app-builder-bin,
which include different default deps for Electron. Libappindicator3-1
is most notable awkward dependency, which is no longer available on
Debian 11. This PR removes it entirely, since it seems to only be
necessary for apps that use the system tray. Updating should hopefully
help with other similar issues though, since other dependencies like
libsecret improve modern OS support here (replacing gnome keyring).

Author: pimterry