Add Python 3.9 compatibility.

[tirkarthi]

• Importing ABC from collections module directly was removed in Python 3.9.
• Fix warnings regarding invalid deprecation warnings.

[OddBloke]

Hi @tirkarthi,

Thanks for the contribution to cloud-init! Before we can land this, we need you to sign the Canonical CLA, which you can find here. Please be sure to include your GitHub username in the submission!

Thanks,

Dan

[tirkarthi]

The CLA asks for my mobile number and address as mandatory along with point of contact from canonical. I am not sure about filling these up.

[OddBloke]

Hi @tirkarthi! Thanks for the response! Those fields are required, unfortunately. For the point of contact, you can put Josh Powers (or me, Daniel Watkins). Let us know if you have any other questions!

[OddBloke]

Hi @tirkarthi, thanks for this submission! As you haven't signed the CLA yet, I'm going to close this out for now. If you do end up signing the CLA, please feel free to reopen (or resubmit) this change and we'll pick it up for review.