Add basic networkx benchmarks

[MridulS]

NetworkX is a pure python library for working with graphs and we use python dictionaries as our core data structure. Python 3.11 did speed up a bunch of our functions, and anything that speeds up python will help us a lot!

Let me know if there is anything else I should add here @mdboom :)

A subset of our ASV benchmarks (py3.11 speed up vs 3.10 and 3.9)

• Betweenness Centrality

• Modularity

• Graph creation