Log Message:
meta-pkgs/ruby-shoulda: udpate to 4.0.0

Update ruby-shoulda to 4.0.0.

## 4.0.0 (2020-06-13)

* `shoulda` now brings in `shoulda-context` 2.0.0, which adds compatibility for
  Ruby 2.7, Rails 6.0, and shoulda-matchers 4.0! Note that there are some
  backward incompatible changes, so please see the [changelog
  entry][shoulda-context-2-0-0] for this release to learn more.