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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


delete:
    description:
      - Specify a list of settings you want to delete.
  description:
    description:
      - Specify the description for the VM. Only used on the configuration web interface.
      - This is saved as comment inside the configuration file.
  digest:
    description:
      - Specify if to prevent changes if current configuration file has different SHA1 digest.
      - This can be used to prevent concurrent modifications.
  force:
    description:
      - Allow to force stop VM.
      - Can be used only with states C(stopped), C(restarted).
    type: bool
  format:
    description:
      - Target drive's backing file's data format.
      - Used only with clone
    default: qcow2
    choices: [ "cloop", "cow", "qcow", "qcow2", "qed", "raw", "vmdk" ]
  freeze:
    description:
      - Specify if PVE should freeze CPU at startup (use 'c' monitor command to start execution).
    type: bool
  full:
    description:
      - Create a full copy of all disk. This is always done when you clone a normal VM.
      - For VM templates, we try to create a linked clone by default.