playbooks: Specify the precise versions of bats-assert & bats-support

See:
https://docs.ansible.com/ansible/latest/collections/ansible/builtin/git_module.html

https://github.com/containers/toolbox/pull/517
https://github.com/containers/toolbox/pull/703

playbooks/setup-env.yaml

@@ -23,12 +23,14 @@
         repo: https://github.com/bats-core/bats-assert
         dest: '{{ zuul.project.src_dir }}/test/system/libs/bats-assert'
         depth: 1
+        version: v2.0.0
 
     - name: Install bats-support library
       git:
         repo: https://github.com/bats-core/bats-support
         dest: '{{ zuul.project.src_dir }}/test/system/libs/bats-support'
         depth: 1
+        version: v0.3.0
 
     - name: Setup environment
       become: yes