PowerGenome/PowerGenome: v0.4.1

A minor release with some bug fixes and feature updates/changes. Fix offshore spur line km to mile conversion Can now read 860m files with different number of header/footer rows Pin xlrd version until we can update to Pandas 1.* Add a settings parameter growth_scenario to select an AEO load growth scenario. The default of REF2020 will be used for now. Change retirement behavior. Plants that retire in a model_year (planning year) will be removed, rather than being retained.