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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


module.fail_json(msg="VM {0} does not exist in cluster.".format(name))
                else:
                    module.fail_json(msg="VM {0} does not exist in cluster.".format(clone))
    if clone is not None:
        if get_vmid(proxmox, name):
            module.exit_json(changed=False, msg="VM with name <%s> already exists" % name)
        if vmid is not None:
            vm = get_vm(proxmox, vmid)
            if not vm:
                module.fail_json(msg='VM with vmid = %s does not exist in cluster' % vmid)
        if not newid:
            try:
                newid = get_nextvmid(module, proxmox)
            except Exception as e:
                module.fail_json(msg="Can't get the next vmid for VM {0} automatically. Ensure your cluster state is good".format(name))
        else:
            vm = get_vm(proxmox, newid)
            if vm:
                module.exit_json(changed=False, msg="vmid %s with VM name %s already exists" % (newid, name))
    if delete is not None:
        try:
            settings(module, proxmox, vmid, node, name, timeout, delete=delete)
            module.exit_json(changed=True, msg="Settings has deleted on VM {0} with vmid {1}".format(name, vmid))
        except Exception as e:
            module.fail_json(msg='Unable to delete settings on VM {0} with vmid {1}: '.format(name, vmid) + str(e))
    elif revert is not None:
        try:
            settings(module, proxmox, vmid, node, name, timeout, revert=revert)
            module.exit_json(changed=True, msg="Settings has reverted on VM {0} with vmid {1}".format(name, vmid))
        except Exception as e: