update dependencies of pygraphviz and silx
update dependencies of pygraphviz and silx (sync silx dependency in requierements-conda and setup.py)
fixes problems due to !1241 (merged)
for now there is no conda-forge package silx 0.10.1, I wrote a mail to DAU to see if they can provide it. Therefor I left the min silx version 0.8 for now but don't enforce it.