Switch to using our ETL derived Population dataset

[danyx23]

The most up to date population dataset that we have at OWID is the one that is created in our ETL pipeline. We should add a script that fetches the latest version of this dataset and transforms it into the form the cartogram needs so that we can easily update the cartograms when the population dataset updates.

To fetch the population dataset in a python script, first pip install the library owid-catalog: pip install owid-catalog, then run this code in python:

from owid import catalog
dataframe = catalog.find('population', namespace="owid", dataset="key_indicators").load()