The timezone support module was used only for changing the timezone in the user module integration tests. Changing the timezone for the tests is unecessarily complex for the purpose of asserting proper parsing of user expiration times.
IMPORTANT
Files under this directory are not actual plugins and modules used by Ansible and as such should not be modified. They are used for testing purposes only (and are temporary).
In almost every case, pull requests affecting files under this directory will be closed.
You are likely looking for something under https://github.com/ansible-collections/ instead.