Add networkx to the list of conda requirements
Add networkx to the list of conda requirements

since networkx is used in `Circuit`
jhillairet/scikit-rf,scikit-rf/scikit-rf,jhillairet/scikit-rf,temmeand/scikit-rf,temmeand/scikit-rf,temmeand/scikit-rf,jhillairet/scikit-rf,scikit-rf/scikit-rf