Align the license with the qutip one

BoxiLi · BoxiLi · commit 6c6df9f591f2 · 2021-07-11T13:07:17.000+02:00
diff --git a/LICENSE b/LICENSE
@@ -1,6 +1,4 @@
-BSD 3-Clause License
-
-Copyright (c) 2020, QuTiP
+Copyright (c) 2011 to 2021 inclusive, QuTiP developers and contributors.
 All rights reserved.
 
 Redistribution and use in source and binary forms, with or without
