There are no racial restrictions. If you choose to play a non-Drow elf, however, you will start play as a slave. Of course, if you want to be a slave, any race is open.
There is really ONE restriction: I do not want to see any non-Evil Drow - especially dual-scimitar wielding ones.
Githyanki is fine. Drow priestess of Lolth is fine. Khrenikath is fine. Troglodytes are fine. Yuan-Ti are fine. If someone has a hankerin' to play Aendryal, that would be fine. Good guys need not apply, though.
This is a good campaign for Charisma based skills as much of it usually revolves around intrigue... although I haven't had a chance to design this adventure yet, so I can't promise this to be the case in this specific adventure.