Tests fail without scipy #2275
Description
Description
Doing a clean install of Cartopy with pip install .[test] ends up with 5 failures and 3 errors due to missing scipy imports. We could either make these optional tests, or add scipy to the testing optional install. Further, would we want to add the other optional things to the test installation? test = ["cartopy[ows,plotting,speedups]", ... i.e. should the testing option be as complete as possible, or should those truly only be if people want to test those branches?
FAILED lib/cartopy/tests/mpl/test_mpl_integration.py::test_quiver_regrid - ImportError: Regridding vectors requires scipy.
FAILED lib/cartopy/tests/mpl/test_mpl_integration.py::test_quiver_regrid_with_extent - ImportError: Regridding vectors requires scipy.
FAILED lib/cartopy/tests/mpl/test_mpl_integration.py::test_barbs_regrid - ImportError: Regridding vectors requires scipy.
FAILED lib/cartopy/tests/mpl/test_mpl_integration.py::test_barbs_regrid_with_extent - ImportError: Regridding vectors requires scipy.
FAILED lib/cartopy/tests/mpl/test_mpl_integration.py::test_streamplot - ImportError: Regridding vectors requires scipy.
ERROR lib/cartopy/tests/test_img_transform.py
ERROR lib/cartopy/tests/test_vector_transform.py
ERROR lib/cartopy/tests/mpl/test_contour.py