Bump shoulda-matchers from 4.1.2 to 4.2.0

Bumps [shoulda-matchers](https://github.com/thoughtbot/shoulda-matchers) from 4.1.2 to 4.2.0.
- [Release notes](https://github.com/thoughtbot/shoulda-matchers/releases)
- [Changelog](https://github.com/thoughtbot/shoulda-matchers/blob/master/NEWS.md)
- [Commits](https://github.com/thoughtbot/shoulda-matchers/compare/v4.1.2...v4.2.0)

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

Gemfile.lock

@@ -166,7 +166,7 @@ GEM
     http-accept (1.7.0)
     http-cookie (1.0.3)
       domain_name (~> 0.5)
-    i18n (1.7.0)
+    i18n (1.8.1)
       concurrent-ruby (~> 1.0)
     i18n-js (3.5.1)
       i18n (>= 0.6.6)
@@ -369,7 +369,7 @@ GEM
     selenium-webdriver (3.142.7)
       childprocess (>= 0.5, < 4.0)
       rubyzip (>= 1.2.2)
-    shoulda-matchers (4.1.2)
+    shoulda-matchers (4.2.0)
       activesupport (>= 4.2.0)
     simplecov (0.17.1)
       docile (~> 1.1)
@@ -406,7 +406,7 @@ GEM
     turbolinks (5.2.1)
       turbolinks-source (~> 5.2)
     turbolinks-source (5.2.0)
-    tzinfo (1.2.5)
+    tzinfo (1.2.6)
       thread_safe (~> 0.1)
     uglifier (4.2.0)
       execjs (>= 0.3.0, < 3)