Update taskcluster from 0.3.4 to 1.2.0

requirements/common.txt

@@ -164,7 +164,8 @@ certifi==2017.4.17 \
 slugid==1.0.7 --hash=sha256:6dab3c7eef0bb423fb54cb7752e0f466ddd0ee495b78b763be60e8a27f69e779
 
 # Used for Taskcluster auth
-taskcluster==0.3.4 --hash sha256:d4fe5e2a44fe27e195b92830ece0a6eb9eb7ad9dc556a0cb16f6f2a6429f1b65
+taskcluster==1.2.0 \
+    --hash=sha256:15af0b2dceb57c55802f9b4ae2bcf031a013c6c12b1faa2d8ce51f0aeaa5fdc2
 
 graphene-django==1.3 \
     --hash=sha256:6679eaa73768a760aef76e1860a4ca3273db4213f0505dc13cdfa44278e027fc