Merge branch '5.4' into 6.0

* 5.4:
  [Pull Requests] Fix Symfony upstream URL as `git://` isn't supported by Github anymore.

Author: javiereguiluz

contributing/code/pull_requests.rst

@@ -99,7 +99,7 @@ Get the Symfony source code:
 .. code-block:: terminal
 
       $ cd symfony
-      $ git remote add upstream git://github.com/symfony/symfony.git
+      $ git remote add upstream https://github.com/symfony/symfony.git
 
 Check that the current Tests Pass
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~