(fix) Added task to install pip3

Added task to install pip3 addres the zuul issue not finding pip.
The zuul job airship-shipyard-airskiff-deployment failes with:
sudo -H -E pip install 'cmd2<=08.7'
sudo: pip: command not found

Change-Id: Ib43aced2c054ecc38b2ce61377b735543c0a9f9f

tools/gate/playbooks/airskiff-deploy.yaml

@@ -23,6 +23,12 @@
         daemon_reload: yes
         name: systemd-resolved
       become: yes
+    - name: ensure pip3 installed
+      apt:
+        name: "{{ item }}"
+      with_items:
+        - python3-pip
+      become: yes
 
     - name: Clone Required Repositories
       shell: |