[pre-commit.ci] auto fixes from pre-commit.com hooks
for more information, see https://pre-commit.ci
just changing the fillna function makes the whole PR cleaner
For each country we gradually switch industry processes from today's
specific energy carrier usage per ton material output to the
best-in-class energy consumption of tomorrow in the
industry_sector_ratios.csv.
This is done on a per-country basis. The ratio of today to tomorrow's
energy consumption is set with the
config["industry"]["sector_ratios_fraction_future"] parameter.