Fix on differences from previous data
Fix on differences from previous data

We are assuming that buying multiple titles at
the same moment, with the same unit price,
they will end up showing in just one entry.

Fixes #8.

Signed-off-by: Vinicius Kwiecien Ruoso <49338e97bd9d901da0d4abfb5c8d7f1a8832af56@gmail.com>

vkruoso/tesouro-direto,vkruoso/tesouro-direto