Add CI check ensuring interfaces have return types

Author: wouterj

PropertyAccessorInterface.php

@@ -42,6 +42,8 @@ interface PropertyAccessorInterface
      * @throws Exception\InvalidArgumentException If the property path is invalid
      * @throws Exception\AccessException          If a property/index does not exist or is not public
      * @throws Exception\UnexpectedTypeException  If a value within the path is neither object nor array
+     *
+     * @return void
      */
     public function setValue(object|array &$objectOrArray, string|PropertyPathInterface $propertyPath, mixed $value);