Re-added dependency scikit-image.

Signed-off-by: Daniel Scheffler <danschef@gfz-potsdam.de>
3 jobs for enhancement/clean_deps in 4 minutes and 24 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Test
passed #14878
test_py_tools_ds

00:00:28

59.0%
passed #14880
test_py_tools_ds_install

00:03:37

passed #14879
test_styles

00:00:19