feat(general): support for Python 3.9

[heitorlessa]

Issue #, if available:

Description of changes:

Add support for Python 3.9: https://aws.amazon.com/blogs/compute/python-3-9-runtime-now-available-in-aws-lambda/

Checklist

• Meet tenets criteria
• Update tests
• Update docs
• PR title follows conventional commit semantics

Breaking change checklist

RFC issue #:

• Migration process documented
• Implement warnings (if it can live side by side)

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[codecov-commenter]

Codecov Report

Merging #626 (77d14a8) into develop (b2773d5) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop     #626   +/-   ##
========================================
  Coverage    99.95%   99.95%           
========================================
  Files          114      114           
  Lines         4597     4597           
  Branches       254      254           
========================================
  Hits          4595     4595           
  Partials         2        2           

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