Ubuntu 24.04 test fix

[stuzart]

Updated the test to check for a string that works with both Ubuntu 22.04 and 24.04

a test run to show that both work: https://github.com/seek4science/seek/actions/runs/13677186559

This fixes a test but not the underlying issue.

it was caused by slight differences in the libre-office, but underlying problem is described in the following issue

• Problem indexing spreadsheets containing cells spanning multiple rows or columns #2159