Install github3.py, requests, pyyaml on the Ubuntu VMs.
diff --git a/buildkite/install-python36.sh b/buildkite/install-python36.sh
index 2f3209d..f65c5ff 100755
--- a/buildkite/install-python36.sh
+++ b/buildkite/install-python36.sh
@@ -16,4 +16,8 @@
 
 add-apt-repository -y "ppa:deadsnakes/ppa"
 apt-get -qqy update > /dev/null
-apt-get -qqy install python3.6 > /dev/null
+apt-get -qqy install python3.6 python3.6-dev python3.6-venv > /dev/null
+python3.6 -m ensurepip
+
+pip3.6 install requests pyyaml
+pip3.6 install --pre github3.py
diff --git a/buildkite/setup-ubuntu.sh b/buildkite/setup-ubuntu.sh
index 86a0986..9bbca14 100755
--- a/buildkite/setup-ubuntu.sh
+++ b/buildkite/setup-ubuntu.sh
@@ -33,10 +33,8 @@
   git
   python
   python-dev
-  python-pip
   python3
   python3-dev
-  python3-pip
   realpath
   unzip
   wget