Regex matches empty string in entity extraction

[AhmedHathout]

medicines-text-mining-tool/notebooks/2_entity_extraction/functions/entity_extraction_functions.py

Line 22 in bea1efd

return re.sub('[()/-]*', '', string_to_clean).strip()

Not sure if this will have any noticeable performance advantage but I think the * should be replaced with + to avoid matching empty strings between characters