Update composer.json for PHP 7.2

vendor/guzzlehttp/psr7/src/NoSeekStream.php

@@ -1,24 +1,27 @@
 <?php
 
+declare(strict_types=1);
+
 namespace GuzzleHttp\Psr7;
 
 use Psr\Http\Message\StreamInterface;
 
 /**
  * Stream decorator that prevents a stream from being seeked.
- *
- * @final
  */
-class NoSeekStream implements StreamInterface
+final class NoSeekStream implements StreamInterface
 {
     use StreamDecoratorTrait;
 
-    public function seek($offset, $whence = SEEK_SET)
+    /** @var StreamInterface */
+    private $stream;
+
+    public function seek($offset, $whence = SEEK_SET): void
     {
         throw new \RuntimeException('Cannot seek a NoSeekStream');
     }
 
-    public function isSeekable()
+    public function isSeekable(): bool
     {
         return false;
     }