Consider updating igraph / python-igraph

[szhorvat]

igraph is still on version 0.10.10 in this system. A significant number of impactful bugfixes were made since then, and upgrading to igraph 0.10.13 / python-igraph 0.11.6 would make a lot of sense. Please be sure to link to ARPACK 3.9.1 (not 3.9.0, which has a bug that show up with the igraph test suite).