Ruby 2.7 support

[mirelon]

I see the branch https://github.com/activeadmin/arbre/tree/ruby27_warnings
to suppress ruby 2.7 warnings,
but isn't it worth adding support for ruby 2.7 (and following 3.0?)

By adding a new syntax
helpers.send(...) instead of helpers.send(name, *args, &block) here: https://github.com/activeadmin/arbre/blob/master/lib/arbre/element.rb#L181

Is a branch for 2.7 a good idea? Because it won't be compatible with 2.6...

[deivid-rodriguez]

I've seen warnings in that same place but I wasn't planning to use a ruby 2.7 specific syntax to fix it. I think it can be fixed in a backwards compatible way.

Other than that warning, arbre works fine on ruby 2.7, right?

[mirelon]

Yeah, it works fine. I agree with backward-compatible (probably with ruby2_keywords gem: https://www.ruby-lang.org/en/news/2019/12/12/separation-of-positional-and-keyword-arguments-in-ruby-3-0/#a-compatible-delegation)

[deivid-rodriguez]

Yeah, ruby2_keywords could be an option, but it looks really ugly to me, honestly.

I think I would prefer a more verbose and less DRY alternative like:

if RUBY_VERSION >= "2.7"
  # current code adapted to keyword separation
else
  # current code
end

If that would work.