minor #15739 Bump license year of code (94noni)

This PR was merged into the 4.4 branch.

Discussion
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Bump license year of code

I was reading some sub pages of https://symfony.com/doc/current/contributing/index.html and found this
Ref https://github.com/symfony/symfony/blob/4.4/LICENSE

Commits
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3a1f383 Update license.rst

Author: javiereguiluz

contributing/code/license.rst

@@ -5,7 +5,7 @@ Symfony Code License
 
 Symfony code is released under `the MIT license`_:
 
-Copyright (c) 2004-2020 Fabien Potencier
+Copyright (c) 2004-2021 Fabien Potencier
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal