Bump capybara from 2.5.0 to 2.16.1

Bumps [capybara](https://github.com/teamcapybara/capybara) from 2.5.0 to 2.16.1.
- [Changelog](https://github.com/teamcapybara/capybara/blob/master/History.md)
- [Commits](teamcapybara/capybara@2.5.0...2.16.1)

Gemfile

@@ -23,7 +23,7 @@ end
 
 group :test do
   gem 'poltergeist', require: false
-  gem 'capybara', '~> 2.5.0'
+  gem 'capybara', '~> 2.16.1'
   gem 'govuk-content-schema-test-helpers', '~> 1.5'
   gem 'mocha', '~> 1.3.0', require: false
   gem 'shoulda'

Gemfile.lock

@@ -54,8 +54,9 @@ GEM
     binding_of_caller (0.7.3)
       debug_inspector (>= 0.0.1)
     builder (3.2.3)
-    capybara (2.5.0)
-      mime-types (>= 1.16)
+    capybara (2.16.1)
+      addressable
+      mini_mime (>= 0.1.3)
       nokogiri (>= 1.3.3)
       rack (>= 1.0.0)
       rack-test (>= 0.5.4)
@@ -322,7 +323,7 @@ DEPENDENCIES
   asset_bom_removal-rails (~> 1.0.0)
   better_errors
   binding_of_caller
-  capybara (~> 2.5.0)
+  capybara (~> 2.16.1)
   gds-api-adapters (~> 48.0)
   govuk-content-schema-test-helpers (~> 1.5)
   govuk-lint (~> 3.4.0)