Include py.typed file in wheels

[AlexWaygood]

#934 by @DenverCoder1 added inline type annotations and a py.typed file, which is great! Unfortunately, however, the py.typed file hasn't been included in wheels published to PyPI for v2.12.0. This means that if I pip install babel locally, mypy still doesn't recognise babel as a typed library. Running mypy on a file with just import babel in it results in this output from mypy (unless the typeshed types-babel package is installed):

test.py:1: error: Library stubs not installed for "babel"  [import]
test.py:1: note: Hint: "python3 -m pip install types-babel"
test.py:1: note: (or run "mypy --install-types" to install all missing stub packages)
test.py:1: note: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports
Found 1 error in 1 file (checked 1 source file)

The fix is simple: just a one-line addition to setup.py.

Closes #795 (which should maybe have been closed after #934).

[akx]

Is package_data merged with what MANIFEST.in brings in? If not, we'll just want include babel/py.typed in the manifest...

Nope, yep, this does exactly what it should 👍

[codecov]

Codecov Report

Merging #975 (4743881) into master (f5bb5bf) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #975   +/-   ##
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  Coverage   90.91%   90.91%           
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  Files          25       25           
  Lines        4350     4350           
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  Hits         3955     3955           
  Misses        395      395           

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[AlexWaygood]

Thanks!

Is package_data merged with what MANIFEST.in brings in? If not, we'll just want include babel/py.typed in the manifest...

I... hope so. If I'm honest, I'm young enough that I've never maintained a project that uses a MANIFEST.in file or uses setuptools as a build backend (I generally just use hatchling).

[akx]

@AlexWaygood Thanks again. Released in Babel 2.12.1, now on PyPI.

[AlexWaygood]

Confirmed that mypy recognises the library as having inline type annotations with the latest release 🎉