[Currency] Remove obsolete currency code validation

UPGRADE-1.13.md

@@ -899,9 +899,9 @@ and use one of the new attributes accordingly to the type of your class, e.g.:
    in favour of the `Country` constraint.
    Due to that, their translation messages `sylius.country.code.regex` and `sylius.country.code.exact_length` were also removed.
 
-1. The `Length` constraints has been removed from `Sylius\Component\Currency\Model\Currency`
-   in favour of the `Currency`constraint.
-   Due to that, the translation messages `sylius.currency.exact_length` was also removed.
+1. The `Regex` and `Length` constraints have been removed from `Sylius\Component\Currency\Model\Currency`
+   in favour of the `Currency` constraint.
+   Due to that, their translation messages `sylius.currency.regex` and `sylius.currency.exact_length` were also removed.
 
 1. The `Regex` constraint has been removed from `Sylius\Component\Locale\Model\Locale`
    in favour of the `Locale` constraint.

src/Sylius/Bundle/CurrencyBundle/Resources/config/validation/Currency.xml

@@ -27,11 +27,6 @@
                 <option name="message">sylius.currency.code.currency</option>
                 <option name="groups">sylius</option>
             </constraint>
-            <constraint name="Regex">
-                <option name="message">sylius.currency.code.regex</option>
-                <option name="pattern">/^[\w-]*$/</option>
-                <option name="groups">sylius</option>
-            </constraint>
         </property>
     </class>
 </constraint-mapping>

src/Sylius/Bundle/CurrencyBundle/Resources/translations/validators.en.yml

@@ -2,7 +2,6 @@ sylius:
     currency:
         code:
             not_blank: Please choose currency code.
-            regex: Currency code can only be comprised of letters, numbers, dashes and underscores.
             unique: Currency code must be unique.
             currency: This value is not a valid currency code.
         exchange_rate: