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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


- Specify the BIOS implementation.
    choices: ['seabios', 'ovmf']
  boot:
    description:
      - Specify the boot order -> boot on floppy C(a), hard disk C(c), CD-ROM C(d), or network C(n).
      - You can combine to set order.
    default: cnd
  bootdisk:
    description:
      - Enable booting from specified disk. C((ide|sata|scsi|virtio)\d+)
  clone:
    description:
      - Name of VM to be cloned. If C(vmid) is setted, C(clone) can take arbitrary value but required for initiating the clone.
  cores:
    description:
      - Specify number of cores per socket.
    default: 1
  cpu:
    description:
      - Specify emulated CPU type.
    default: kvm64
  cpulimit:
    description:
      - Specify if CPU usage will be limited. Value 0 indicates no CPU limit.
      - If the computer has 2 CPUs, it has total of '2' CPU time
  cpuunits:
    description:
      - Specify CPU weight for a VM.
      - You can disable fair-scheduler configuration by setting this to 0
    default: 1000