Make the pip3 role really install something

It seems that the package module doesn't have a default value for the
state of a package. So not specifying it is essentially a no-op. Specify
state: present so that we really get the packages installed that we want
to have.

Change-Id: Ied9484c74922b9f48e14205b73ca95066a68a87f

playbooks/roles/pip3/tasks/main.yaml

@@ -3,3 +3,4 @@
     name:
       - python3-pip
       - python3-virtualenv
+    state: present