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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


type: bool
  revert:
    description:
      - Revert a pending change.
  sata:
    description:
      - A hash/dictionary of volume used as sata hard disk or CD-ROM. C(sata='{"key":"value", "key":"value"}').
      - Keys allowed are - C(sata[n]) where 0 ≤ n ≤ 5.
      - Values allowed are -  C("storage:size,format=value").
      - C(storage) is the storage identifier where to create the disk.
      - C(size) is the size of the disk in GB.
      - C(format) is the drive's backing file's data format. C(qcow2|raw|subvol).
  scsi:
    description:
      - A hash/dictionary of volume used as SCSI hard disk or CD-ROM. C(scsi='{"key":"value", "key":"value"}').
      - Keys allowed are - C(sata[n]) where 0 ≤ n ≤ 13.
      - Values allowed are -  C("storage:size,format=value").
      - C(storage) is the storage identifier where to create the disk.
      - C(size) is the size of the disk in GB.
      - C(format) is the drive's backing file's data format. C(qcow2|raw|subvol).
  scsihw:
    description:
      - Specifies the SCSI controller model.
    choices: ['lsi', 'lsi53c810', 'virtio-scsi-pci', 'virtio-scsi-single', 'megasas', 'pvscsi']
  serial:
    description:
      - A hash/dictionary of serial device to create inside the VM. C('{"key":"value", "key":"value"}').
      - Keys allowed are - serial[n](str; required) where 0 ≤ n ≤ 3.
      - Values allowed are - C((/dev/.+|socket)).
      - /!\ If you pass through a host serial device, it is no longer possible to migrate such machines - use with special care.