minor symfony#13537 typo date (zairigimad)

This PR was submitted for the 5.0 branch but it was merged into the 3.4 branch instead.

Discussion
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typo date

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Commits
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f969015 typo

Author: javiereguiluz

contributing/code/license.rst

@@ -5,7 +5,7 @@ Symfony Code License
 
 Symfony code is released under `the MIT license`_:
 
-Copyright (c) 2004-2019 Fabien Potencier
+Copyright (c) 2004-2020 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