Updated the gsutil version used by download_from_google_storage.

`download_from_google_storage --config` is currently failing. It still uses gsutil 4.26 but 4.28 has been added recently:

https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/801355

Using 4.28 fixes the bug.

Bug: 796937
Change-Id: I299da7ede8087d832cd6e193d8fc4198a6878c6c
Reviewed-on: https://chromium-review.googlesource.com/840007
Reviewed-by: Jochen Eisinger <jochen@chromium.org>
Reviewed-by: John Budorick <jbudorick@chromium.org>
Commit-Queue: Joao da Silva <joaodasilva@chromium.org>

download_from_google_storage.py

@@ -60,7 +60,7 @@ class Gsutil(object):
   RETRY_BASE_DELAY = 5.0
   RETRY_DELAY_MULTIPLE = 1.3
 
-  def __init__(self, path, boto_path=None, timeout=None, version='4.26'):
+  def __init__(self, path, boto_path=None, timeout=None, version='4.28'):
     if not os.path.exists(path):
       raise FileNotFoundError('GSUtil not found in %s' % path)
     self.path = path