Fix warnings caused by library code when running system tests #1060
Description
Running system tests locally produces the following (under Python 3.8, if it matters, on the v3 branch):
UserWarning: Geometry is in a geographic CRS. Results from 'area' are likely incorrect. Use 'GeoSeries.to_crs()' to re-project geometries to a projected CRS before this operation.
The tests should be refactored to not cause these warnings.
FWIW, there is one other Shapely deprecation warning, but that is caused by Pandas core, no our own code.