TST: Force scikit-image dev in devdeps

Author: pllim

tox.ini

@@ -49,6 +49,8 @@ extras =
     predeps: all
 
 commands =
+    # Force scikit-image upgrade to workaround mysterious pin in the stack.
+    devdeps: pip install scikit-image>=0.0.dev0 -U --pre -I https://pypi.anaconda.org/scientific-python-nightly-wheels/simple
     pip freeze
     pytest --pyargs acstools {toxinidir}/doc {posargs}