Remove awesome_nested_set gem dependency

Gemfile

@@ -10,8 +10,6 @@ gem "tzinfo-data", platforms: %i[ mingw mswin x64_mingw jruby ]
 
 gem "devise"
 
-gem 'awesome_nested_set'
-
 gem 'importmap-rails', '~> 1.2.3'
 # turborails >= 2.0.0 required with npm v8.0.0 with support for [autofocus]
 # attribute in turbo-streams

Gemfile.lock

@@ -77,8 +77,6 @@ GEM
       tzinfo (~> 2.0)
     addressable (2.8.6)
       public_suffix (>= 2.0.2, < 6.0)
-    awesome_nested_set (3.6.0)
-      activerecord (>= 4.0.0, < 7.2)
     base64 (0.2.0)
     bcrypt (3.1.20)
     bigdecimal (3.1.5)
@@ -251,7 +249,6 @@ PLATFORMS
   x86_64-linux
 
 DEPENDENCIES
-  awesome_nested_set
   byebug
   capybara
   devise

app/models/unit.rb

@@ -11,9 +11,6 @@ class Unit < ApplicationRecord
     errors.add(:base, :multilevel_nesting)
   end
 
-  acts_as_nested_set parent_column: :base_id, scope: :user, dependent: :destroy,
-    order_column: :multiplier
-
   scope :defaults, ->{ where(user: nil) }
   scope :ordered, ->{
     parent_symbol = Arel::Nodes::NamedFunction.new(