fix zoom-in/zoom-out using mouse wheel

regression introduced by 2393:235f847be37e "python3 support: pylint, W1619 #(old-division) division w/o __future__ statement"

[main]
host = https://www.transifex.com

[beremiz-ide.beremiz]
file_filter = Beremiz_<lang>.po
minimum_perc = 0
source_file = messages.pot
source_lang = en
type = PO