check the version in about menu
Closes windows#152 (closed)
This adds a simple version check to the about menu.
This behavior can be enabled by setting the pref librewolf.aboutMenu.checkVersion to true.
You can also change the librewolf.aboutMenu.versionCheckGitlabUrl pref to use a different url for checking the releases, for example for the windows repo: https://gitlab.com/api/v4/projects/13852981/releases