Bug 1460475 - Upgrade python-zstandard in image_builder; r=dustin

Version 0.9.0 bundles a newer version of the zstandard library, which
is a little faster and has a few minor bug fixes (none that we were
likely hitting, however).

MozReview-Commit-ID: 9YgSZ0G41eg

--HG--
extra : rebase_source : 8f5a68323b1e1fe7e9f1dd1a92e132434972d21d

taskcluster/docker/image_builder/download-and-compress

@@ -9,7 +9,7 @@ import time
 
 import requests
 import requests_unixsocket
-import zstd
+import zstandard as zstd
 
 # Allow requests to fetch from UNIX domain sockets.
 requests_unixsocket.monkeypatch()

taskcluster/docker/image_builder/setup.sh

@@ -39,17 +39,17 @@ cd /setup
 tooltool_fetch <<EOF
 [
   {
-    "size": 463794,
+    "size": 558068,
     "visibility": "public",
-    "digest": "c6ba906403e5c18b374faf9f676b10f0988b9f4067bd6c52c548d7dee58fac79974babfd5c438aef8da0a5260158116db69b11f2a52a775772d9904b9d86fdbc",
+    "digest": "72b1fc542e5af36fc660d7b8d3882f0a25644d3b66316293717aabf9ba8cf578e49e2cf45e63e962c5535ec1f8b3e83248c379d34b0cab2ef1a950205ad153ce",
     "algorithm": "sha512",
-    "filename": "zstandard-0.8.0.tar.gz"
+    "filename": "zstandard-0.9.0.tar.gz"
   }
 ]
 EOF
 )
 
-/usr/bin/pip -v install /setup/zstandard-0.8.0.tar.gz
+/usr/bin/pip -v install /setup/zstandard-0.9.0.tar.gz
 
 # python-pip only needed to install python-zstandard. Removing it removes
 # several hundred MB of dependencies from the image.