MAINT : added default_benchmark_timeout to asv.conf.json

[Schefflera-Arboricola]

For 800 node graphs, the benchmarks fail and give a timeout error(60.0 s).

[dschult]

I couldn't find default_benchmark_timeout in the docs for asv.
Where did you find that? it's a nice thing to be able to set. :)

[Schefflera-Arboricola]

I couldn't find default_benchmark_timeout in the docs for asv.
Where did you find that? it's a nice thing to be able to set. :)

here airspeed-velocity/asv#1308
Also after increasing the default timeout here #42 i was no longer getting the timeout error.

[dschult]

I approve this PR.
I make a comment below, but it doesn't need to be changed here unless you want to.