[FIX] l10n_be_intrastat: weight must be > 0.01

Fine tuning of 06d149a3
It appears that according to
https://www.nbb.be/doc/dq/f_pdf_ex/nieuwsbriefintrastat_n28_2018_fr.pdf


minimum weight  is 0.01, and that anything below should be rounded to 0.01

OPW 2031682

closes odoo/odoo#34951

Signed-off-by: Lucas Perais (lpe) <lpe@odoo.com>