[FIX] l10n_it_withholding_tax: Prevent "TypeError: 'bool' object is not iterable"
[FIX] l10n_it_withholding_tax: Prevent "TypeError: 'bool' object is not iterable"

OCA/l10n-italy,dcorio/l10n-italy,dcorio/l10n-italy,dcorio/l10n-italy,OCA/l10n-italy,OCA/l10n-italy