<!--- Verify first that your issue is not already reported on GitHub -->
<!--- Also test if the latest release and devel branch are affected too -->
<!--- Complete *all* sections as described, this form is processed automatically -->

##### SUMMARY
<!--- Explain the problem briefly below -->

`python-gitlab` library release a new version [v1.13.0](https://github.com/python-gitlab/python-gitlab/releases/tag/v1.13.0). User/Password authentication as been removed completely causing all Ansible GitLab module to fail... 

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
<!--- Write the short name of the module, plugin, task or feature below, use your best guess if unsure -->

gitlab_group
gitlab_deploy_key
gitlab_hook
gitlab_project
gitlab_project_variable
gitlab_runner
gitlab_user

##### ANSIBLE VERSION
<!--- Paste verbatim output from "ansible --version" between quotes -->
All versions

type: dict
'''
EXAMPLES = '''
- name: Set or update some CI/CD variables
  gitlab_project_variable:
    api_url: https://gitlab.com
    api_token: secret_access_token
    project: markuman/dotfiles
    purge: false
    vars:
      ACCESS_KEY_ID: abc123
      SECRET_ACCESS_KEY: 321cba
- name: Delete one variable
  gitlab_project_variable:
    api_url: https://gitlab.com
    api_token: secret_access_token
    project: markuman/dotfiles
    state: absent
    vars:
      ACCESS_KEY_ID: abc123
'''
RETURN = '''
project_variable:
  description: Four lists of the variablenames which were added, updated, removed or exist.
  returned: always
  type: dict
  contains:
    added:
      description: A list of variables which were created.
      returned: always