Upgrade benchmark-driver version
as I already started to use --runner=block introduced in v0.14.20 like: https://github.com/ruby/ruby/pull/2321#issuecomment-518638663
Upgrade benchmark-driver version
as I already started to use --runner=block introduced in v0.14.20 like:
https://github.com/ruby/ruby/pull/2321#issuecomment-518638663