move `git_archive_all{ → /__init__}.py`

[nim65s]

Hi,

The current distribution archives are not including py.typed and *.pyi, because the git_archive_all module don't contain them. As a result, on a project which has git_archive_all as dependency, mypy shows: error: Skipping analyzing "git_archive_all": module is installed, but missing library stubs or py.typed marker [import]

A fix for this is to re-organize the module from name.py to name/__init__.py to be able to include other files in name/.

To validate this, here are the logs of python -m wheel -v .

• Before this PR:

  creating '/tmp/pip-wheel-wuabr55j/git_archive_all-1.23.1-py2.py3-none-any.whl' and adding 'build/bdist.linux-x86_64/wheel' to it
  adding 'git_archive_all.py'
  adding 'git_archive_all-1.23.1.dist-info/LICENSE.txt'
  adding 'git_archive_all-1.23.1.dist-info/METADATA'
  adding 'git_archive_all-1.23.1.dist-info/WHEEL'
  adding 'git_archive_all-1.23.1.dist-info/entry_points.txt'
  adding 'git_archive_all-1.23.1.dist-info/top_level.txt'
  adding 'git_archive_all-1.23.1.dist-info/zip-safe'
  adding 'git_archive_all-1.23.1.dist-info/RECORD'
  removing build/bdist.linux-x86_64/wheel
  Building wheel for git-archive-all (setup.py) ... done

• and after this PR:

  creating '/tmp/pip-wheel-dulgau14/git_archive_all-1.23.1-py2.py3-none-any.whl' and adding 'build/bdist.linux-x86_64/wheel' to it
  adding 'git_archive_all/__init__.py'
  adding 'git_archive_all/__init__.pyi'
  adding 'git_archive_all/py.typed'
  adding 'git_archive_all-1.23.1.dist-info/LICENSE.txt'
  adding 'git_archive_all-1.23.1.dist-info/METADATA'
  adding 'git_archive_all-1.23.1.dist-info/WHEEL'
  adding 'git_archive_all-1.23.1.dist-info/entry_points.txt'
  adding 'git_archive_all-1.23.1.dist-info/top_level.txt'
  adding 'git_archive_all-1.23.1.dist-info/zip-safe'
  adding 'git_archive_all-1.23.1.dist-info/RECORD'
  removing build/bdist.linux-x86_64/wheel
  Building wheel for git-archive-all (setup.py) ... done

[nim65s]

While here, I'm also adding a type hint for the main function, to fix the following mypy error:

error: Module has no attribute "main"  [attr-defined]