Does ramsey/uuid version 4 use "true" or pseudo-random numbers?

I'm using ramsey/uuid in my project. I'm creating new data entities with uuid4, which generates random UUIDs:

Uuid::uuid4();

But I'm using this approach while bulk importing many thousands of data too. Now I'm worrying about the entropy pool of my system: does uuid4 use a "true" random number which will deplete my entropy pool at some time? Or will it use pseudo-random numbers and I don't have to worry about?

Thanks a lot!