Remove deprecated license_file from setup.cfg

[jdufresne]

Starting with wheel 0.32.0 (2018-09-29), the "license_file" option is
deprecated.

https://wheel.readthedocs.io/en/stable/news.html

The wheel will continue to include LICENSE, it is now included
automatically:

https://wheel.readthedocs.io/en/stable/user_guide.html#including-license-files-in-the-generated-wheel-file

[McSinyx]

While this is true for wheels, it does not apply for source distribution. At the time of writing, setuptools have yet to support license_files so I guess we'll have to stick to the wheel-deprecated option.

[jdufresne]

The source distribution continues to include the LICENSE.txt file. There is no additional action required for it and we don't need to rely on a deprecated feature to do it. It is included by the MANIFEST.in file:

appdirs/MANIFEST.in

Line 3 in f8a8e9d

include LICENSE.txt

This is easy to demonstrate by running python3 setup.py sdist then inspecting the .tar.gz file. Here is what I see:

 drwxrwxr-x     jon/jon           0 appdirs-1.4.4/
 -rw-rw-r--     jon/jon        3668 appdirs-1.4.4/CHANGES.rst
 -rw-rw-r--     jon/jon        1097 appdirs-1.4.4/LICENSE.txt
 -rw-rw-r--     jon/jon          90 appdirs-1.4.4/MANIFEST.in
 -rw-rw-r--     jon/jon       11250 appdirs-1.4.4/PKG-INFO
 -rw-rw-r--     jon/jon        4345 appdirs-1.4.4/README.rst
 drwxrwxr-x     jon/jon           0 appdirs-1.4.4/appdirs.egg-info/
 -rw-rw-r--     jon/jon       11250 appdirs-1.4.4/appdirs.egg-info/PKG-INFO
 -rw-rw-r--     jon/jon         234 appdirs-1.4.4/appdirs.egg-info/SOURCES.txt
 -rw-rw-r--     jon/jon           1 appdirs-1.4.4/appdirs.egg-info/dependency_links.txt
 -rw-rw-r--     jon/jon           8 appdirs-1.4.4/appdirs.egg-info/top_level.txt
 -rw-rw-r--     jon/jon       25018 appdirs-1.4.4/appdirs.py
 -rw-rw-r--     jon/jon          67 appdirs-1.4.4/setup.cfg
 -rw-rw-r--     jon/jon        2101 appdirs-1.4.4/setup.py
 drwxrwxr-x     jon/jon           0 appdirs-1.4.4/test/
 -rw-rw-r--     jon/jon           0 appdirs-1.4.4/test/__init__.py
 -rw-rw-r--     jon/jon        1309 appdirs-1.4.4/test/test_api.py

Notice LICENSE.txt is still included.

[McSinyx]

You are right, I missed that. With license_file in setup.cfg alone setuptools can find the file but since we want to maximize compatibility MANIFEST.in is a better choice.

[zoofood]

LGTM