Remove six as dependency

[hawflau]

Issue #, if available:

Description of changes:

• Remove six

Description of how you validated changes:

Checklist:

• Add/update tests using:
  • Correct values
  • Bad/wrong values (None, empty, wrong type, length, etc.)
  • Intrinsic Functions
• make pr passes
• Update documentation
• Verify transformed template deploys and application functions as expected

Examples?

Please reach out in the comments, if you want to add an example. Examples will be
added to sam init through https://github.com/awslabs/aws-sam-cli-app-templates/

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov-commenter]

Codecov Report

Merging #2302 (f9f02c2) into develop (e7a1496) will increase coverage by 0.79%.
The diff coverage is 96.36%.

@@             Coverage Diff             @@
##           develop    #2302      +/-   ##
===========================================
+ Coverage    93.58%   94.38%   +0.79%     
===========================================
  Files           90       97       +7     
  Lines         6124     7065     +941     
  Branches      1260     1435     +175     
===========================================
+ Hits          5731     6668     +937     
+ Misses         183      181       -2     
- Partials       210      216       +6     

Impacted Files	Coverage Δ
samtranslator/model/api/http_api_generator.py	91.18% <70.00%> (ø)
samtranslator/model/api/api_generator.py	93.69% <88.33%> (-0.67%)	⬇️
samtranslator/__init__.py	100.00% <100.00%> (ø)
samtranslator/feature_toggle/dialup.py	100.00% <100.00%> (ø)
samtranslator/feature_toggle/feature_toggle.py	100.00% <100.00%> (+12.16%)	⬆️
samtranslator/intrinsics/actions.py	98.78% <100.00%> (+0.06%)	⬆️
samtranslator/intrinsics/resource_refs.py	95.83% <100.00%> (-0.17%)	⬇️
samtranslator/metrics/method_decorator.py	100.00% <100.00%> (ø)
samtranslator/metrics/metrics.py	100.00% <100.00%> (ø)
samtranslator/model/__init__.py	97.63% <100.00%> (-0.02%)	⬇️
... and 40 more

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