Update to support Slurm 20.11

[everner]

When is support for Slurm 20.11 planned? I think there's more urgency now in light of SchedMD's decision to make v19 and previous versions of 20.02 and 20.11 unavailable for download because of the latest security vulnerability.

Due to a security vulnerability (CVE-2021-31215), all versions of Slurm prior to 20.11.7 or 20.02.7 are no longer available for download.

https://schedmd.com/archives.php

[tazend]

Hi, I think I can give it a go when I have time and prepare a pull request. Means, adjusting the current pyslurm definition file(s) to make it compile with 20.11

[samarjeet]

Would it be possible to support version 21.08 as well?