color cell background not working

[yuanjing1]

I tweaked in package xlsx_writer, made color change in font:
from ap(ret, '<color ' || xlsx.fonts(f).color || '/>');
to ap(ret, '<color rgb="' || xlsx.fonts(f).color || '"/>');

but would like to change background color.

[gpalleschi]

Hi I have forked this project https://github.com/gpalleschi/xlsx_writer-Oracle and improved filler functionality and other stuffs.