Marks PostCode::setService() and PostCode::getService() as deprecated

Fixes #6

Signed-off-by: Frank Brückner <dev@froschdesignstudio.de>

src/Validator/PostCode.php

@@ -302,6 +302,9 @@ public function setFormat($format)
     /**
      * Returns the actual set service
      *
+     * @deprecated since 2.12.0, this method will be removed in version 3.0.0 of this component.
+     *             Additional validations should be done via a validation chain.
+     *
      * @return mixed|null
      */
     public function getService()
@@ -312,6 +315,9 @@ public function getService()
     /**
      * Sets a new callback for service validation
      *
+     * @deprecated since 2.12.0, this method will be removed in version 3.0.0 of this component.
+     *             Additional validations should be done via a validation chain.
+     *
      * @param mixed|null $service
      * @return $this
      */