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##### SUMMARY
An hour ago I upgraded my Proxmox to the new stable version 6. Since then my playbooks fail with this error:
`fatal: [proxmox]: FAILED! => {"changed": false, "msg": "authorization on proxmox cluster failed with exception: could not convert string to float: '6.0-4'"}`

It seems like the proxmox changed the API.

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
proxmox (https://github.com/mrdrogdrog/ansible/blob/6430205d396b7c1733de22a898c51823f67d5bf4/lib/ansible/modules/cloud/misc/proxmox.py#L484)

##### ANSIBLE VERSION
<!--- Paste verbatim output from "ansible --version" between quotes -->
```
ansible 2.8.2
  config file = /etc/ansible/ansible.cfg
  configured module search path = ['/home/tilman/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/lib/python3.7/site-packages/ansible
  executable location = /usr/bin/ansible
  python version = 3.7.3 (default, Jun 24 2019, 04:54:02) [GCC 9.1.0]
```


##### OS / ENVIRONMENT
Proxmox 6 


##### STEPS TO REPRODUCE
- Use the latest ansible version
- Use the latest stable version of proxmox (6)
- Use the proxmox module to do anything. E.g. create a container
- Get the error


##### EXPECTED RESULTS
Normal runthrough

##### ACTUAL RESULTS
Crash with an error


if update:
        if 'virtio' in kwargs:
            del kwargs['virtio']
        if 'sata' in kwargs:
            del kwargs['sata']
        if 'scsi' in kwargs:
            del kwargs['scsi']
        if 'ide' in kwargs:
            del kwargs['ide']
        if 'net' in kwargs:
            del kwargs['net']
    # Convert all dict in kwargs to elements. For hostpci[n], ide[n], net[n], numa[n], parallel[n], sata[n], scsi[n], serial[n], virtio[n]
    for k in list(kwargs.keys()):
        if isinstance(kwargs[k], dict):
            kwargs.update(kwargs[k])
            del kwargs[k]
    # Rename numa_enabled  to numa. According the API documentation
    if 'numa_enabled' in kwargs:
        kwargs['numa'] = kwargs['numa_enabled']
        del kwargs['numa_enabled']
    # -args and skiplock require root@pam user
    if module.params['api_user'] == "root@pam" and module.params['args'] is None:
        if not update:
            kwargs['args'] = vm_args
    elif module.params['api_user'] == "root@pam" and module.params['args'] is not None:
        kwargs['args'] = module.params['args']
    elif module.params['api_user'] != "root@pam" and module.params['args'] is not None:
        module.fail_json(msg='args parameter require root@pam user. ')
    if module.params['api_user'] != "root@pam" and module.params['skiplock'] is not None:
        module.fail_json(msg='skiplock parameter require root@pam user. ')