Update all LICENSE Copyright year

LICENSE

@@ -1,4 +1,4 @@
-Copyright (c) 2006-2019 SymPy Development Team
+Copyright (c) 2006-2020 SymPy Development Team
 
 All rights reserved.
 
@@ -32,8 +32,8 @@ DAMAGE.
 Patches that were taken from the Diofant project (https://github.com/diofant/diofant)
 are licensed as:
 
-Copyright (c) 2006-2017 SymPy Development Team,
-              2013-2017 Sergey B Kirpichev
+Copyright (c) 2006-2018 SymPy Development Team,
+              2013-2020 Sergey B Kirpichev
 
 All rights reserved.
 
@@ -101,7 +101,7 @@ DAMAGE.
 The files under the directory sympy/parsing/autolev/tests/pydy-example-repo
 are directly copied from PyDy project and are licensed as:
 
-Copyright (c) 2009-2019, PyDy Authors
+Copyright (c) 2009-2020, PyDy Authors
 All rights reserved.
 
 Redistribution and use in source and binary forms, with or without