Remove voucher validation on code format

The code doesn't rely on label match any more so this restriction
is not necessary anymore

app/models/voucher.rb

@@ -13,9 +13,6 @@ class Voucher < ApplicationRecord
            dependent: :nullify
 
   validates :code, presence: true, uniqueness: { scope: :enterprise_id }
-  # We store the tax portion of a voucher in a separate adjustment with a label starting by "Tax"
-  # when tax are exluded from price. To avoid any issue we a code stating by Tax in not allowed
-  validates :code, format: { without: /\ATax/ }
 
   TYPES = ["Vouchers::FlatRate", "Vouchers::PercentageRate"].freeze
 

config/locales/en.yml

@@ -117,10 +117,6 @@ en:
             using_producer_stock_settings_but_count_on_hand_set: "must be blank because using producer stock settings"
             on_demand_but_count_on_hand_set: "must be blank if on demand"
             limited_stock_but_no_count_on_hand: "must be specified because forcing limited stock"
-        voucher:
-          attributes:
-            code:
-              invalid: "can't start with 'Tax'"
       messages:
         confirmation: "doesn't match %{attribute}"
         blank: "can't be blank"

spec/models/voucher_spec.rb

@@ -28,11 +28,6 @@ describe Voucher do
 
     it { is_expected.to validate_presence_of(:code) }
     it { is_expected.to validate_uniqueness_of(:code).scoped_to(:enterprise_id) }
-    it "doesn't accept code starting with 'Tax'" do
-      voucher = build(:voucher_flat_rate, code: 'Taxnew_code', enterprise: enterprise)
-
-      expect(voucher.valid?).to be(false)
-    end
   end
 
   describe '#display_value' do