This was missed in the pcolormesh refactor causing some incorrect
bounds calculations when plotting the data.

Natural Earth version 5 updated some features, which caused
this test to fail the tolerance. Update the image with the new
features and remove the old forced edgecolor.

There is some conda-forge issue with Shapely/geos
so switch over to Linux for the min dependency tests.

This branch has a different set of updates, causing some of the
test tolerances to be changed. Two of these natural earth tests
are different because the shapefiles have recently been updated
and some features are different now. (For instance, the lakes
in the shapefile are now different)

The negotiation with a tile provider needed more up-to-date
TLS/SSL protocols, so for now we just pin to a lower openssl
on the runners.

Partial cherry-pick of 579be04
to increase the test tolerance of the images for MPL3.5 tests.