Tests take too long to complete

[phoebe-p]

Not really a bug, but some tests take a long time to complete, particularly those in test_compare_methods which compare absorption profiles calculated with the angular redistribution matrix method and with just ray-tracing or TMM. It's necessary to use a lot of angle bins/rays to allow convergence and good agreement with the "pure" RT/TMM methods, but also very slow. Should try to find a middle ground which does not take as long to complete on GitHub Actions, or perhaps run these tests separately (scheduled).