If that is all you need to do, then there are multiple other ways to do this. The simplest would be to use a light-dependent resistor/photoresistor. When light hits the LDR, the resistance decreases. Depending on your ambient light situation, minor additional circuitry might be needed.
Also, you could sense the voltage that is applied to the light bulb (if you know what you're doing when working with mains voltages if the bulb is so powered) instead of the current. An optoisolator would be needed to isolate the Pi.
There are also current transformers available, termed AC current switches, that incorporate a current transformer and a solid state switch that would be suitable for connection directly to a GPIO pin (a pullup resistor may be needed). The current transformer goes around one leg feeding the bulb, and will provide a contact closure output when the current passing through it is above a threshold.
https://www.nktechnologies.com/current- ... -switches/