It's pretty much safe sex.
Oral sex in general is safe from most things, but particular performing oral on a woman is the safest.
I can't think of anything you would get from licking pussy.
-Chlamydia almost never infects the throat
-Gonorrhea does like the throat, but how does it get to the throat from licking? I dunno.
-HIV, no
-Warts, no
- Syphilis, yes, but exceedingly rare disease is straight people and oral transmission is not so common either
-Genital herpes infecting the mouth? Nah, not really readily transmitted this way. Maybe a few cases have been documented due to it's rarity.