fix deprecation warnings found during running tests

[mikedlr]

Running some test cases I got a bunch of deprecation warnings.

This is a very simple patch to eliminate those. Mostly trivial docstring changes but one set of collections abstract base class changes which will cause compatibility problems with python 3.8.

[mikedlr]

I think that #1675 fixes the reason why my tests were calling in to the vendored code.

[codecov-io]

Codecov Report

Merging #1674 into develop will increase coverage by 0.35%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop    #1674      +/-   ##
===========================================
+ Coverage    92.07%   92.42%   +0.35%     
===========================================
  Files           53       53              
  Lines         9824     9871      +47     
===========================================
+ Hits          9045     9123      +78     
+ Misses         779      748      -31

Impacted Files	Coverage Δ
botocore/eventstream.py	100% <0%> (ø)	⬆️
botocore/parsers.py	99.79% <0%> (+0.01%)	⬆️
botocore/model.py	97.81% <0%> (+0.04%)	⬆️
botocore/utils.py	97.62% <0%> (+0.16%)	⬆️
botocore/hooks.py	96.38% <0%> (+0.4%)	⬆️
botocore/handlers.py	97.11% <0%> (+0.42%)	⬆️
botocore/compat.py	93.92% <0%> (+4.97%)	⬆️
botocore/awsrequest.py	98.36% <0%> (+5.9%)	⬆️

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[Jamim]

Hello @jamesls,

Could you please take a look at this PR?

Thanks!

[nateprewitt]

This file ended up getting removed when we unvendored urllib3. It should now be compliant when installing a current version of urllib3. Thanks for the contribution!