update strsim to 0.8
@ignatenkobrain Hmm, is this worth doing? It looks like strsim 0.8 requires a newer version of Rust, so this probably means a docopt 1.1 release. I guess I'm fine with that, but I also feel like strsim 0.7 is doing fine?
As usual, I don't want to package multiple versions of package in Fedora and I would prefer to not carry downstream patch.
I don't know whether that's a sustainable policy moving forward long term, but I'm happy to keep pushing. I filed an issue with strsim for now: https://github.com/dguo/strsim-rs/issues/26 --- Once they add a Rust version to their CI config, can you add that same version to this PR? After that, I'll do a 1.1 release.