upstream ci: Fix ansible-lint errors due to missing collections

When running ansible-lint it tries to load and syntax check the
playbooks it evaluates, and if any of the modules used in the playbooks
can't be found, it fails with a fatal error, as if there was a syntax
error.

By adding a 'requirements.yml' file with all the collections that are
used in any playbook (be it a runtime, test, or development dependency),
forces ansible-lint to install and use the collections in its virtual
environment, successfully parsing the playbook files.

See more at ansible/ansible-lint#4048 and
ansible/ansible-lint#4049.

requirements.yml

@@ -0,0 +1,7 @@
+# These collections are only required for testing and development.
+# You should be able to use ansible-freeipa without installing these.
+---
+collections:
+  - name: ansible.posix
+  - name: community.docker
+  - name: containers.podman