fix: retirement pipeline pip version (openedx-unsupported#7046)

* fix: retirement pipeline pip version

With configured version of the pip (19.0.3) it is impossible to install
the cryptography package with version higher than 39.X.X
(starting from the palm release it is 40+, source:
https://github.com/openedx/tubular/blob/open-release/palm.3/requirements/base.txt#L47)

In this PR I use the COMMON_PIP_VERSION.

playbooks/roles/user_retirement_pipeline/defaults/main.yml

@@ -26,7 +26,7 @@ retirement_service_venv_dir: "{{ retirement_service_home }}/venv"
 retirement_service_user_shell: "/bin/bash"
 retirement_service_script_path: "{{ retirement_service_app_dir }}/scripts"
 
-retirement_service_pip_version: "19.0.3"
+retirement_service_pip_version: "{{ COMMON_PIP_VERSION }}"
 
 retirement_service_environment:
   PATH: '{{ retirement_service_venv_dir }}/bin:{{ ansible_env.PATH }}'