gs: update to latest 4.57 release

BUG=None
TEST=`gs_unittest --network` passes for py2 & py3

Change-Id: I10ac48beaccb8c217661d5a476b194f314992ff5
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/2637067
Tested-by: Mike Frysinger <vapier@chromium.org>
Auto-Submit: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Chris McDonald <cjmcdonald@chromium.org>
Reviewed-by: Chris McDonald <cjmcdonald@chromium.org>
diff --git a/lib/gs.py b/lib/gs.py
index 18a11c4..e20817d 100644
--- a/lib/gs.py
+++ b/lib/gs.py
@@ -325,7 +325,7 @@
   # (1*sleep) the first time, then (2*sleep), continuing via attempt * sleep.
   DEFAULT_SLEEP_TIME = 60
 
-  GSUTIL_VERSION = '4.51'
+  GSUTIL_VERSION = '4.57'
   GSUTIL_TAR = 'gsutil_%s.tar.gz' % GSUTIL_VERSION
   GSUTIL_URL = (PUBLIC_BASE_HTTPS_URL +
                 'chromeos-mirror/gentoo/distfiles/%s' % GSUTIL_TAR)