TOX: Pillow is hard to build on CI

Author: effigies

tox.ini

@@ -45,7 +45,7 @@ description = Pytest with coverage
 labels = test
 install_command =
   python -I -m pip install \
-    --only-binary numpy,scipy,h5py
+    --only-binary numpy,scipy,h5py,pillow \
     --extra-index-url https://pypi.anaconda.org/scientific-python-nightly-wheels/simple \
     {opts} {packages}
 pip_pre =