I've just run
on Raspbian, but when I try
apt-get install python3-gpiozero python-gpiozero
it can't find either package.
Can't find any evidence of needing a non-standard apt-repository. How do I install it?
The command you used should work according to the Pi Foundation's recent blog post, however, I tried it and got the same error. I believe doing a dist-upgrade should solve the problem. To upgrade do the following:
sudo apt-get update
sudo apt-get dist-upgrade
then rerun the command to install gpiozero:
sudo apt-get install python-gpiozero python3-gpiozero
If that does not work or you want to upgrade to Jessie this post contains the necessary steps.