Python 3.6 baggage code removal

[hallvictoria]

Description

Fixes # https://github.com/Azure/azure-functions-pyfx-planning/issues/139 // https://github.com/Azure/azure-functions-pyfx-planning/issues/176

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PR information

• The title of the PR is clear and informative.
• There are a small number of commits, each of which has an informative message. This means that previously merged commits do not appear in the history of the PR. For information on cleaning up the commits in your pull request, see this page.
• If applicable, the PR references the bug/issue that it fixes in the description.
• New Unit tests were added for the changes made and CI is passing.

Quality of Code and Contribution Guidelines

• I have read the contribution guidelines.

[codecov]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (5f352af) 85.46% compared to head (ae10d6e) 85.45%.

Files	Patch %	Lines
azure_functions_worker/main.py	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #1419      +/-   ##
==========================================
- Coverage   85.46%   85.45%   -0.02%     
==========================================
  Files          35       35              
  Lines        1968     1966       -2     
  Branches      370      370              
==========================================
- Hits         1682     1680       -2     
  Misses        213      213              
  Partials       73       73              

Flag	Coverage Δ
unittests	85.40% <60.00%> (-0.02%)	⬇️

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[vrdmr]

We should be able to remove aio_compat.py as well as rethink if we need typing_inspect.py itself.

[vrdmr]

LGMT

Take a look at the docker tests as well to ensure it passes.