remove pywavelets from CI (#1833)

Author: emmanuelle

packages/python/plotly/tox.ini

@@ -74,7 +74,6 @@ deps=
     optional: pillow==5.2.0
     optional: matplotlib==2.2.3
     optional: xarray==0.10.9
-    optional: pywavelets==1.0.3
     optional: scikit-image==0.14.4
 
 ; CORE ENVIRONMENTS