Update page id (URL)

app/models/form/sales/pages/sale_date.rb

@@ -1,7 +1,7 @@
 class Form::Sales::Pages::SaleDate < ::Form::Page
   def initialize(id, hsh, subsection)
     super
-    @id = "sale_date"
+    @id = "completion_date"
     @header = ""
     @description = ""
     @subsection = subsection

spec/models/form/sales/pages/sale_date_spec.rb

@@ -16,7 +16,7 @@ RSpec.describe Form::Sales::Pages::SaleDate, type: :model do
   end
 
   it "has the correct id" do
-    expect(page.id).to eq("sale_date")
+    expect(page.id).to eq("completion_date")
   end
 
   it "has the correct header" do

spec/models/form/sales/subsections/setup_spec.rb

@@ -13,7 +13,7 @@ RSpec.describe Form::Sales::Subsections::Setup, type: :model do
 
   it "has correct pages" do
     expect(setup.pages.map(&:id)).to eq(
-      %w[organisation created_by purchaser_code sale_date],
+      %w[organisation created_by purchaser_code completion_date],
     )
   end