bug: fix nonfree tests execution

[Neurone]

Description:

Nonfree env variable name was wrong.

Related issue(s):

N/A

Notes for reviewer:

Rust CI / test for this PR fails because now it is executed as expected ;)

Checklist

• [x] Documented (Code comments, README, etc.)
• [x] Tested (unit, integration, etc.)

[Neurone]

Note: Rust CI / test fails because now it is executed as expected ;)