Alex the pendant is grounded already. You have the three wires coming out of the pendant. The green is the ground. From what I saw of your ballast, you want to take the green from the pendant to the ground on the ballast input. Your ballast has two outputs to the bulb. Yellow & green I think I remember it to be. These wires would go to the bulb wires (black & white). So another words the ground from the pendant goes to the ground from the wall except you can catch it at your input to the ballast. Grounded DONE!

HTH
Robert