No, this isn't part of that set. It could have been taken at the same time (if it is real), but the rest of the pics were posted in b&w, so IDK. (Liz's eyebrows do look similar in both though, though, and they've gone through a few different looks over time)
The pic isn't a high enough quality to really determine for certain, but it holds up ok as close as I can look in photoshop. The bottom of Ari's hair in the back has a few odd white spots, but if it is photo-shopped it was done well enough that something like that would have been an easy fix for the photoshopper to make.
There's just to many image-quality artifacts to find (or disprove) any photoshopping artifacts. And them teasing this certainly isn't out of line with other pictures I've seen. I just can't say for sure, but I like the pic so until proven otherwise I'm going to go with it being real.