Revert Python 3.9 compatibility in test_iovs

The following discussion from !4931 (merged) should be addressed:

• @clemenci started a discussion: (+2 comments)

  I accidentally used a function introduced with Python 3.11, and we still use Python 3.9 (LCG 105c).

  94b393eb fixes the problem but it should be reverted once we switch to LCG 106.

created branch 384-revert-python-3-9-compatibility-in-test_iovs to address this issue

mentioned in merge request !4932

mentioned in merge request Run2Support!67