<!--- 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
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


vga=module.params['vga'],
                      virtio=module.params['virtio'],
                      watchdog=module.params['watchdog'])
            if not clone:
                get_vminfo(module, proxmox, node, vmid,
                           ide=module.params['ide'],
                           net=module.params['net'],
                           sata=module.params['sata'],
                           scsi=module.params['scsi'],
                           virtio=module.params['virtio'])
            if update:
                module.exit_json(changed=True, msg="VM %s with vmid %s updated" % (name, vmid))
            elif clone is not None:
                module.exit_json(changed=True, msg="VM %s with newid %s cloned from vm with vmid %s" % (name, newid, vmid))
            else:
                module.exit_json(changed=True, msg="VM %s with vmid %s deployed" % (name, vmid), **results)
        except Exception as e:
            if update:
                module.fail_json(msg="Unable to update vm {0} with vmid {1}=".format(name, vmid) + str(e))
            elif clone is not None:
                module.fail_json(msg="Unable to clone vm {0} from vmid {1}=".format(name, vmid) + str(e))
            else:
                module.fail_json(msg="creation of %s VM %s with vmid %s failed with exception=%s" % (VZ_TYPE, name, vmid, e))
    elif state == 'started':
        try:
            vm = get_vm(proxmox, vmid)
            if not vm:
                module.fail_json(msg='VM with vmid <%s> does not exist in cluster' % vmid)
            if getattr(proxmox.nodes(vm[0]['node']), VZ_TYPE)(vmid).status.current.get()['status'] == 'running':
                module.exit_json(changed=False, msg="VM %s is already running" % vmid)