Add budget image to Budget and image factories and model

spec/factories/files.rb

@@ -8,6 +8,10 @@ FactoryBot.define do
       association :imageable, factory: :proposal
     end
 
+    trait :budget_image do
+      association :imageable, factory: :budget
+    end
+
     trait :budget_investment_image do
       association :imageable, factory: :budget_investment
     end

spec/models/budget_spec.rb

@@ -6,6 +6,7 @@ describe Budget do
   it_behaves_like "sluggable", updatable_slug_trait: :drafting
   it_behaves_like "reportable"
   it_behaves_like "globalizable", :budget
+  it_behaves_like "acts as imageable", :budget_image
 
   describe "scopes" do
     describe ".open" do

spec/models/image_spec.rb

@@ -2,6 +2,7 @@ require "rails_helper"
 
 describe Image do
   it_behaves_like "image validations", "budget_investment_image"
+  it_behaves_like "image validations", "budget_image"
   it_behaves_like "image validations", "proposal_image"
 
   it "stores attachments with Active Storage" do