Change to CRS for calculating centroid

[fnands]

When calculating overlap geopandas raises a warning:

skysat_stereo_workflow.py:43: UserWarning: Geometry is in a geographic CRS. Results from 'centroid' are likely incorrect. Use 'GeoSeries.to_crs()' to re-project geometries to a projected CRS before this operation.

I implemented the solution from here, which changes to an equidistant projection before centroid calculation.

In practice, we are not dealing with huge distances here, so probably overkill, but gets geopandas to shut up and technically the correct thing to do.