Bump shoulda-matchers from 4.2.0 to 4.3.0 (#1555)

Bumps [shoulda-matchers](https://github.com/thoughtbot/shoulda-matchers) from 4.2.0 to 4.3.0.
- [Release notes](https://github.com/thoughtbot/shoulda-matchers/releases)
- [Changelog](https://github.com/thoughtbot/shoulda-matchers/blob/master/NEWS.md)
- [Commits](thoughtbot/shoulda-matchers@v4.2.0...v4.3.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Gemfile.lock

@@ -213,7 +213,7 @@ GEM
     selectize-rails (0.12.6)
     sentry-raven (2.13.0)
       faraday (>= 0.7.6, < 1.0)
-    shoulda-matchers (4.2.0)
+    shoulda-matchers (4.3.0)
       activesupport (>= 4.2.0)
     sprockets (4.0.0)
       concurrent-ruby (~> 1.0)