### Description

Ensures the TURBOPACK env is always explicitly set before running tests

x-ref: [slack
thread](https://vercel.slack.com/archives/C04KC8A53T7/p1696278216418089)

### Testing Instructions

Test run verifying this fix can be seen here
https://github.com/vercel/turbo/actions/runs/6386995577/job/17334817140