Remove Python 3.6 compatibility code from datetime2timestamp()

[akx]

The library has targeted 3.7+ since #2684; no need to retain compatibility code that is never called.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (54a09c7) 93.47% compared to head (d87da0e) 93.47%.

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Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #3062   +/-   ##
========================================
  Coverage    93.47%   93.47%           
========================================
  Files           66       66           
  Lines        14031    14029    -2     
========================================
- Hits         13115    13114    -1     
+ Misses         916      915    -1     

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[nateprewitt]

Thanks for the PR @akx. While we don't officially support Python 3.6, we still have some downstreams that are consuming current versions of botocore using Python 3.6. We've intentionally left a few of these changes and our syntax upgrade setup to avoid unnecessarily breaking this.

That said, we have changes staged for our upcoming Python 3.7 deprecation that will address some of this. I can leave this open to be integrated into that branch or we can resolve this as a duplicate.

[akx]

@nateprewitt Thanks – I'm curious: how are those downstreams using new botocores when a python_requires='>=3.7' is in place? Just pip install --ignore-requires-python and hope for the best? 😁

[nateprewitt]

Unfortunately, there are still distant reaches that don't rely on pip or any of the PyPA infrastructure to manage their Python packages. We'll hopefully be leaving that behind shortly 😉

[nateprewitt]

Ok, we're ready to ship 3.7 deprecation. This should be good to go.

I saw the other PR, we still have some concerns around the original windows issue that lead to that PR. It's likely safe to clean up as you've suggested but we'll need to do some manual testing first.