Remove unused gem Turn

It provides runners for MiniTest and we use RSpec.

Gemfile

@@ -103,7 +103,6 @@ gem 'ofn-qz', github: 'openfoodfoundation/ofn-qz', ref: '60da2ae4c44cbb4c8d602f5
 
 group :test, :development do
   # Pretty printed test output
-  gem 'turn', '~> 0.8.3', require: false
   gem 'fuubar', '~> 2.2.0'
   gem 'rspec-rails', ">= 3.5.2"
   gem 'shoulda-matchers'

Gemfile.lock

@@ -183,7 +183,6 @@ GEM
       tilt
     angularjs-file-upload-rails (1.1.6)
     angularjs-rails (1.5.5)
-    ansi (1.4.2)
     arel (3.0.3)
     ast (2.3.0)
     atomic (1.1.99)
@@ -668,8 +667,6 @@ GEM
     turbo-sprockets-rails3 (0.3.6)
       railties (> 3.2.8, < 4.0.0)
       sprockets (>= 2.0.0)
-    turn (0.8.3)
-      ansi
     tzinfo (0.3.53)
     uglifier (2.7.1)
       execjs (>= 0.3.0)
@@ -798,7 +795,6 @@ DEPENDENCIES
   timecop
   truncate_html
   turbo-sprockets-rails3
-  turn (~> 0.8.3)
   uglifier (>= 1.0.3)
   unicorn
   unicorn-rails