Update pip and setuptools before installing requirements

We are seeing the kayobe-overcloud-ubuntu-focal CI job fail while
deploying Tenks with:

    ModuleNotFoundError: No module named 'pkg_resources.extern.six'

Updating pip and setuptools to the latest allowed in upper constraints
appears to fix it.

Change-Id: Ida85adca948664d7d4427edd6c3ab15fd75fb3fe

ansible/roles/ironic-enrolment/tasks/main.yml

@@ -9,6 +9,17 @@
     - not lookup('env', 'OS_USERNAME')
     - not lookup('env', 'OS_CLOUD')
 
+- name: Ensure the latest versions of pip and setuptools are installed
+  pip:
+    name: "{{ item.name }}"
+    state: latest # noqa package-latest
+    virtualenv: "{{ ironic_virtualenv_path }}"
+    extra_args: >-
+      -c {{ ironic_python_upper_constraints_url }}
+  with_items:
+    - { name: pip }
+    - { name: setuptools }
+
 # This is useful to get a uniquely generated temporary path.
 - name: Create temporary file for pip requirements
   tempfile: