Simplify the contains method

Author: Webklex

src/Attribute.php

@@ -170,12 +170,7 @@ public function merge(array $values, bool $strict = false): Attribute {
  * @return bool
  */
  public function contains($value): bool {
- foreach ($this->values as $v) {
- if ($v === $value) {
- return true;
- }
- }
- return false;
+ return in_array($value, $this->values, true);
  }
 
  /**