Update flipflop to latests released version

Gemfile

@@ -97,7 +97,7 @@ gem 'scenic'
 
 gem 'sanitize-url'
 
-gem 'flipflop', github: 'voormedia/flipflop'
+gem 'flipflop'
 
 # Cron jobs
 gem 'delayed_job_active_record'

Gemfile.lock

@@ -1,10 +1,3 @@
-GIT
-  remote: git://github.com/voormedia/flipflop.git
-  revision: a6e639c6c631cdb5e74cb84a1a2a314ca3420579
-  specs:
-    flipflop (2.3.1)
-      activesupport (>= 4.0)
-
 GIT
   remote: https://github.com/breckenedge/delayed_job_web.git
   revision: 6bcb10e61ea2b9a44ffa16be8536dff46ad51449
@@ -210,6 +203,8 @@ GEM
     ffi (1.9.23)
     fission (0.5.0)
       CFPropertyList (~> 2.2)
+    flipflop (2.4.0)
+      activesupport (>= 4.0)
     fog (1.42.0)
       fog-aliyun (>= 0.1.0)
       fog-atmos
@@ -810,7 +805,7 @@ DEPENDENCIES
   dotenv-rails
   draper
   factory_bot
-  flipflop!
+  flipflop
   fog
   fog-openstack
   font-awesome-rails