Adds condition for dev environment only

We don't want to enable this in production just yet

db/migrate/20240715103415_enable_admin_style_v3_by_default.rb

@@ -1,5 +1,7 @@
 class EnableAdminStyleV3ByDefault < ActiveRecord::Migration[7.0]
   def up
-    Flipper.enable(:admin_style_v3)
+    if Rails.env.development?
+      Flipper.enable(:admin_style_v3)
+    end
   end
 end