Upgrade pip before installing zuul

The new cryptography release needs either a recent pip to be able to
use abi3 wheels or a rust compiler on the system to make the source
installation work. Thus upgrade pip to use the wheels.

Change-Id: I4024a89e54de8bbb4e90cbe152a1504e31515fa8
Depends-On: https://review.opendev.org/c/zuul/zuul-jobs/+/775511

roles/nodepool-zuul-functional/tasks/main.yaml

@@ -1,6 +1,8 @@
 - name: Install packages
   shell:
-    cmd: sudo pip3 install -e .
+    cmd: |+
+      sudo pip3 install --upgrade pip setuptools wheel
+      sudo pip3 install -e .
     chdir: "{{ zuul.projects['opendev.org/zuul/nodepool'].src_dir }}"
 
 - name: Run zuul-nodepool-integration/start.sh