Merge branch '4.4' into 5.4

* 4.4:
  Remove 5.3 from PR template
  Bump Symfony version to 4.4.38
  Update VERSION for 4.4.37
  Update CONTRIBUTORS for 4.4.37
  Update CHANGELOG for 4.4.37
  [Process] Update PHPDoc to use proper placeholder syntax
  Fixed functional testing description

Process.php

@@ -176,7 +176,7 @@ public function __construct(array $command, string $cwd = null, array $env = nul
      * In order to inject dynamic values into command-lines, we strongly recommend using placeholders.
      * This will save escaping values, which is not portable nor secure anyway:
      *
-     *   $process = Process::fromShellCommandline('my_command "$MY_VAR"');
+     *   $process = Process::fromShellCommandline('my_command "${:MY_VAR}"');
      *   $process->run(null, ['MY_VAR' => $theValue]);
      *
      * @param string         $command The command line to pass to the shell of the OS