Merge branch '6.4' into 7.0

* 6.4:
  Ensure all properties have a type

Author: nicolas-grekas

Transport/Smtp/Stream/AbstractStream.php

@@ -24,8 +24,11 @@
  */
 abstract class AbstractStream
 {
+    /** @var resource|null */
     protected $stream;
+    /** @var resource|null */
     protected $in;
+    /** @var resource|null */
     protected $out;
 
     private string $debug = '';