Upgrade criterion to 0.5.1

[faern]

trafficstars

Upgrade criterion to the latest version. Mostly to get rid of complaints from cargo audit and not have to ignore known issues. But also because having the latest can be nice.

[faern]

Got stuck on clap requiring newer rustc. I'm really not a proponent for strict MSRV. But it's a bit silly to require clap here. I created https://github.com/bheisler/criterion.rs/issues/781 to see if we can get rid of it in a cleaner way maybe.