fix: Don't auto-install updates when user quits the app

[tatoalo]

when a pending update was downloaded and the user quit, the before-quit handler called quitAndInstall(), restarting the app instead of closing it

squirrel already stages downloaded updates, so the next manual launch applies the update automatically, no restart needed

[charlesvien]

I can see how this is a conflicting user intent, I want to quit the app not quit and then have it reopen on me because there is an update. I lost context on the original change behind this but if I recall it was not actually updating the app on the next restart, we've done a lot of updates since then tho- happy to merge and if we have reports come in we can handle it in a more graceful way.