add PEP-396 version attribute to sagemaker module

[jesterhazy]

Issue #, if available:

#434

Description of changes:

add PEP-396 version attribute to sagemaker module

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[codecov-io]

Codecov Report

Merging #435 into master will decrease coverage by 0.14%.
The diff coverage is 100%.

@@            Coverage Diff            @@
##           master    #435      +/-   ##
=========================================
- Coverage   93.75%   93.6%   -0.15%     
=========================================
  Files          55      55              
  Lines        4032    4033       +1     
=========================================
- Hits         3780    3775       -5     
- Misses        252     258       +6

Impacted Files	Coverage Δ
src/sagemaker/__init__.py	100% <100%> (ø)	⬆️
src/sagemaker/local/image.py	88.92% <0%> (-1.9%)	⬇️

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[nadiaya]

I believe we should follow pep-0396 guidance https://www.python.org/dev/peps/pep-0396/#classic-distutils :
In classic distutils, the simplest way to add the version string to the setup() function in setup.py is to do something like this:

from elle import __version__
setup(name='elle', version=__version__)

In the PEP author's experience however, this can fail in some cases, such as when the module uses automatic Python 3 conversion via the 2to3 program (because setup.py is executed by Python 3 before the elle module has been converted).

In that case, it's not much more difficult to write a little code to parse the version from the file rather than importing it. Without providing too much detail, it's likely that modules such as distutils2 will provide a way to parse version strings from files. E.g.:

from distutils2 import get_version
setup(name='elle', version=get_version('elle.py'))

[nadiaya]

Nevermind, from offline conversation that seems to be the new way (especially since Distutils2 development is stopped):
https://packaging.python.org/guides/single-sourcing-package-version/