Fix flakyness of test "should update the expires property of the session using Session\#touch() even if rolling is false"

[Uzlopak]

Prerequisites

• [X] I have written a descriptive issue title
• [X] I have searched existing issues to ensure the issue has not already been raised

Issue

see https://github.com/fastify/session/runs/8139620859?check_suite_focus=true

Probably we need to increase the waiting period here https://github.com/fastify/session/blob/c67dc0ded1e146a9bbf34c2a2e5ddf5b740c3376/test/session.test.js#L381