Think Gen Z is still spending the summer scooping ice cream and begging for shift swaps at a beach snack shack? In reality, they’re more likely to be speed-running your DoorDash order than clocking in anywhere with a manager. New data shows workers under 26 are the most rapidly growing group signing up for gig apps like Uber and DoorDash this summer, according to mobile analytics firm Apptopia .  Registrations among Gen Z are up 8.4% compared to last year. Translation: the “summer job” is