Add Python 3.10 support

[joguSD]

Updates the CRT version to match the latest version of botocore:

boto/botocore#2523

Ran the integ tests locally on Python 3.10 as well.

[codecov-commenter]

Codecov Report

Merging #58 (ce9f11a) into develop (316906c) will not change coverage.
The diff coverage is 0.00%.

❗ Current head ce9f11a differs from pull request most recent head 0d2ccfe. Consider uploading reports for the commit 0d2ccfe to get more accurate results

@@           Coverage Diff            @@
##           develop      #58   +/-   ##
========================================
  Coverage    88.77%   88.77%           
========================================
  Files           34       34           
  Lines         1925     1925           
========================================
  Hits          1709     1709           
  Misses         216      216           

Flag	Coverage Δ
unittests	88.77% <0.00%> (ø)

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Impacted Files	Coverage Δ
setup.py	0.00% <0.00%> (ø)

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[nateprewitt]

Hmm, looks like 3.10 isn't happy about something.

TypeError: required field "lineno" missing from alias

[nateprewitt]

Oh, this needs to be pytest==6.2.5.