Update systemd-netshot with AmbientCapabilities

[maniack]

If you want the service to listen on privileged ports when starting the service as unprivileged user, it is better to use systemd's built-in functionality than scripts in if-up.d

https://www.freedesktop.org/software/systemd/man/systemd.exec.html#AmbientCapabilities=

[SCadilhac]

Thanks!