scripts: Update copyright in `common_codegen.py`

Change-Id: Id5049a260cb8521a1768b6b48b36bdef825e5508
diff --git a/scripts/common_codegen.py b/scripts/common_codegen.py
index b301b3a..9744bb3 100644
--- a/scripts/common_codegen.py
+++ b/scripts/common_codegen.py
@@ -1,8 +1,8 @@
 #!/usr/bin/python3 -i
 #
-# Copyright (c) 2015-2017, 2019 The Khronos Group Inc.
-# Copyright (c) 2015-2017, 2019 Valve Corporation
-# Copyright (c) 2015-2017, 2019 LunarG, Inc.
+# Copyright (c) 2015-2017, 2019-2021 The Khronos Group Inc.
+# Copyright (c) 2015-2017, 2019-2021 Valve Corporation
+# Copyright (c) 2015-2017, 2019-2021 LunarG, Inc.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -23,10 +23,10 @@
 # Copyright text prefixing all headers (list of strings).
 prefixStrings = [
     '/*',
-    '** Copyright (c) 2015-2017, 2019 The Khronos Group Inc.',
-    '** Copyright (c) 2015-2017, 2019 Valve Corporation',
-    '** Copyright (c) 2015-2017, 2019 LunarG, Inc.',
-    '** Copyright (c) 2015-2017, 2019 Google Inc.',
+    '** Copyright (c) 2015-2017, 2019-2021 The Khronos Group Inc.',
+    '** Copyright (c) 2015-2017, 2019-2021 Valve Corporation',
+    '** Copyright (c) 2015-2017, 2019-2021 LunarG, Inc.',
+    '** Copyright (c) 2015-2017, 2019-2021 Google Inc.',
     '**',
     '** Licensed under the Apache License, Version 2.0 (the "License");',
     '** you may not use this file except in compliance with the License.',