Add some new packages to the test images
This MR adds some packages that we need for upcoming/recent changes the test images.
-
dill
. I don't know why this is currently missing, but gets installed at the start of every test job. -
skimage
. This is needed for running the logo example that now runs on schedules. -
celerite
/george
. These are required for !1086 (merged). -
bilby-cython
. Needed for !1053 (merged).