adjustments for prow

Author: sbueringer

hack/ci/e2e-conformance-gcp-prepare.sh

@@ -133,7 +133,8 @@ main() {
   fi
   if ! command -v openstack;
   then
-    pip install python-cinderclient python-glanceclient python-keystoneclient python-neutronclient python-novaclient python-openstackclient python-octaviaclient
+    apt-get update && DEBIAN_FRONTEND=noninteractive apt-get install -y python3-dev
+    pip3 install python-cinderclient python-glanceclient python-keystoneclient python-neutronclient python-novaclient python-openstackclient python-octaviaclient
   fi
 
   # Wait until cloud-init is done