[TEST] AIBL-to-BIDS utils are lacking unit tests for sessions.tsv creation

[AliceJoubert]

The function creating sessions files for AIBL:

clinica/clinica/iotools/converters/aibl_to_bids/utils/clinical.py

Lines 151 to 155 in 48c12ab

	def create_sessions_tsv_file(
	input_path: Path,
	clinical_data_dir: Path,
	clinical_specifications_folder: Path,
	) -> None:

is currently not tested. The utility functions used in it as well.