Remove use of setuptools_scm_git_archive

Change to assert_allclose instead of assert_almost_equal to test
small changes as recommended by Numpy's testing docs. This is due
to small tolerance changes with PROJ 9.0.1.

These only minimally changed with a shifting of the dashes in the
gridlines, but no substantive changes.

Depending on the values input to Nightshade, the floating point
precision could put the range for arccos outside of [-1, 1], which
in turn numpy returns as nan's, yielding bad geometries further
downstream. This patch clips the arccos calculations to [-1, 1] to
guarantee we aren't out of the valid floating point bounds.

Apparently the images change between PROJ 9.0.0 and 9.0.1