Bump spring from 2.0.2 to 2.1.0

Bumps [spring](https://github.com/rails/spring) from 2.0.2 to 2.1.0.
- [Release notes](https://github.com/rails/spring/releases)
- [Changelog](https://github.com/rails/spring/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rails/spring/compare/v2.0.2...v2.1.0)

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

Gemfile.lock

@@ -146,7 +146,7 @@ GEM
       bootstrap (~> 4.1.3)
       rails (>= 4.2.0)
       sass-rails
-    i18n (1.6.0)
+    i18n (1.7.0)
       concurrent-ruby (~> 1.0)
     io-like (0.3.0)
     jmespath (1.3.1)
@@ -180,7 +180,7 @@ GEM
     mimemagic (0.3.3)
     mini_mime (1.0.1)
     mini_portile2 (2.4.0)
-    minitest (5.11.3)
+    minitest (5.12.2)
     minitest-capybara (0.8.2)
       capybara (~> 2.2)
       minitest (~> 5.0)
@@ -266,8 +266,7 @@ GEM
       childprocess (~> 0.5)
       rubyzip (~> 1.2, >= 1.2.2)
     slack-notifier (2.3.2)
-    spring (2.0.2)
-      activesupport (>= 4.2)
+    spring (2.1.0)
     spring-watcher-listen (2.0.1)
       listen (>= 2.7, < 4.0)
       spring (>= 1.2, < 3.0)