Add support for PHP 8.1

src/Type/Integer.php

@@ -15,9 +15,11 @@ declare(strict_types=1);
 namespace Ramsey\Uuid\Type;
 
 use Ramsey\Uuid\Exception\InvalidArgumentException;
+use ValueError;
 
 use function ctype_digit;
 use function ltrim;
+use function sprintf;
 use function strpos;
 use function substr;
 
@@ -114,6 +116,14 @@ final class Integer implements NumberInterface
         return $this->toString();
     }
 
+    /**
+     * @return array{string: string}
+     */
+    public function __serialize(): array
+    {
+        return ['string' => $this->toString()];
+    }
+
     /**
      * Constructs the object from a serialized string representation
      *
@@ -126,4 +136,16 @@ final class Integer implements NumberInterface
     {
         $this->__construct($serialized);
     }
+
+    /**
+     * @param array{string: string} $data
+     */
+    public function __unserialize(array $data): void
+    {
+        if (!isset($data['string'])) {
+            throw new ValueError(sprintf('%s(): Argument #1 ($data) is invalid', __METHOD__));
+        }
+
+        $this->unserialize($data['string']);
+    }
 }