docs(copyright): correct name of company for commits after 2015 (#440)

diff --git a/google/auth/jwt.py b/google/auth/jwt.py
index 06e7679..cdd69ac 100644
--- a/google/auth/jwt.py
+++ b/google/auth/jwt.py
@@ -1,4 +1,4 @@
-# Copyright 2016 Google Inc.
+# Copyright 2016 Google LLC
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.