Update capybara to 3.31 (#32453, #32907).

Patch by Pavel Rosický.


git-svn-id: http://svn.redmine.org/redmine/trunk@19493 e93f8b46-1217-0410-a6f0-8f06a7374b81

Gemfile

@@ -84,7 +84,7 @@ group :test do
   gem "ffi", platforms: [:mingw, :x64_mingw, :mswin]
   # For running system tests
   gem 'puma'
-  gem "capybara", (RUBY_VERSION < "2.4" ? "~> 3.15.1" : "~> 3.29.0")
+  gem 'capybara', (RUBY_VERSION < '2.4' ? '~> 3.15.1' : '~> 3.31.0')
   gem "selenium-webdriver"
   # RuboCop
   gem 'rubocop', '~> 0.79.0'