Bug 1203970: Upgrade phone-builder image for tc-vcs 2.3.12 r=garndt

testing/docker/phone-builder/Dockerfile

@@ -1,4 +1,4 @@
-FROM          taskcluster/builder:0.5.8
+FROM          taskcluster/builder:0.5.9
 MAINTAINER    Wander Lairson Costa <wcosta@mozilla.com>
 
 ENV           SOCORRO_SYMBOL_UPLOAD_TOKEN_FILE /home/worker/socorro.token

testing/docker/phone-builder/VERSION

@@ -1 +1 @@
-0.0.19
+0.0.20