Suppress `warning: too many arguments for format string`
Suppress `warning: too many arguments for format string`

`Style/OptionalArguments` cop has a warning of MRI.

```bash
$ RUBYOPT=-w bundle exec rspec spec/rubocop/cop/style/optional_arguments_spec.rb
/home/pocke/.gem/ruby/2.4.0/gems/parser-2.4.0.0/lib/parser/lexer.rb:10922: warning: assigned but unused variable - testEof
/home/pocke/.gem/ruby/2.4.0/gems/parallel-1.11.2/lib/parallel.rb:222: warning: shadowing outer local variable - args
/home/pocke/.gem/ruby/2.4.0/gems/parallel-1.11.2/lib/parallel.rb:227: warning: shadowing outer local variable - args
Run options:
  include {:focus=>true}
  exclude {:broken=>#<Proc:./spec/spec_helper.rb:39>}

All examples were filtered out; ignoring {:focus=>true}

Randomized with seed 20102

RuboCop::Cop::Style::OptionalArguments
/home/pocke/ghq/github.com/bbatsov/rubocop/lib/rubocop/cop/style/optional_arguments.rb:30: warning: too many arguments for format string
  registers an offense when an optional argument is followed by a required argument
  allows methods with only optional arguments
  allows methods with only one required argument
  allows methods with only required arguments
  allows methods with multiple optional arguments at the end
  allows methods with only one optional argument
  allows methods without arguments
/home/pocke/ghq/github.com/bbatsov/rubocop/lib/rubocop/cop/style/optional_arguments.rb:30: warning: too many arguments for format string
/home/pocke/ghq/github.com/bbatsov/rubocop/lib/rubocop/cop/style/optional_arguments.rb:30: warning: too many arguments for format string
  registers an offense for each optional argument when multiple optional arguments are followed by a required argument
  named params
    with default values
      allows optional arguments before an optional named argument
    required params
/home/pocke/ghq/github.com/bbatsov/rubocop/lib/rubocop/cop/style/optional_arguments.rb:30: warning: too many arguments for format string
      registers an offense for optional arguments that come before required arguments where there are name arguments
      allows optional arguments before required named arguments
      allows optional arguments to come before a mix of required and optional named argument

Finished in 0.10693 seconds (files took 0.69272 seconds to load)
12 examples, 0 failures

Randomized with seed 20102
```

This change suppresses the warning.

meganemura/rubocop,lumeet/rubocop,b-t-g/rubocop,bbatsov/rubocop,sue445/rubocop,haziqhafizuddin/rubocop,deivid-rodriguez/rubocop,pocke/rubocop,scottmatthewman/rubocop,vergenzt/rubocop,panthomakos/rubocop,tdeo/rubocop,mikegee/rubocop,Drenmi/rubocop,deivid-rodriguez/rubocop,iGEL/rubocop,maxjacobson/rubocop,urbanautomaton/rubocop,bbatsov/rubocop,maxjacobson/rubocop,meganemura/rubocop,tejasbubane/rubocop,alexcstark/rubocop,tdeo/rubocop,mikegee/rubocop,meganemura/rubocop,panthomakos/rubocop,mikegee/rubocop,alexcstark/rubocop,deivid-rodriguez/rubocop,maxjacobson/rubocop,lumeet/rubocop,smakagon/rubocop,jfelchner/rubocop,akihiro17/rubocop,panthomakos/rubocop,haziqhafizuddin/rubocop,petehamilton/rubocop,jmks/rubocop,tejasbubane/rubocop,petehamilton/rubocop,jfelchner/rubocop,palkan/rubocop,rrosenblum/rubocop,petehamilton/rubocop,akihiro17/rubocop,iGEL/rubocop,tejasbubane/rubocop,NobodysNightmare/rubocop,NobodysNightmare/rubocop,jmks/rubocop,jmks/rubocop,tdeo/rubocop,rrosenblum/rubocop,urbanautomaton/rubocop,sue445/rubocop,palkan/rubocop,vergenzt/rubocop,scottmatthewman/rubocop,akihiro17/rubocop,palkan/rubocop,b-t-g/rubocop,bquorning/rubocop,jfelchner/rubocop,pocke/rubocop,smakagon/rubocop,rrosenblum/rubocop,vergenzt/rubocop,bquorning/rubocop,bquorning/rubocop,sue445/rubocop,Drenmi/rubocop