Fixed rename causing tutorial to fail.
Fixed rename causing tutorial to fail.

Currently set up as if we are passing a dataframe. Tutorial fails at eemeter.metered_savings(), step 48.
TypeError: rename() got an unexpected keyword argument 'columns'

Signed-off-by: Phillips <6c49109ec5d4a7069558e909ed17b72f9555d99e@dnvgl.com>

openeemeter/eemeter,openeemeter/eemeter