Catch IndexError when getting dir creation date

Description

Index error means that there are no files in the directory. We catch this error, as we want get_dir_creation_date to raise only a ValueError, which highlights better that the provided run is incorrect.

Previous changes broke the tests.

How Has This Been Tested?

pytest -vv tests/test_cal_tools.py

Types of changes

• Bug fix (non-breaking change which fixes an issue)

Checklist:

Reviewers