COPYING: it's 2020!

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COPYING

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 COPYRIGHT AND PERMISSION NOTICE
 
-Copyright (c) 1996 - 2019, Daniel Stenberg, <daniel@haxx.se>, and many
+Copyright (c) 1996 - 2020, Daniel Stenberg, <daniel@haxx.se>, and many
 contributors, see the THANKS file.
 
 All rights reserved.