Update packaging: add `MANIFEST.in` and `py.typed`

[sugatoray]

This PR addresses the following two aspects of pypi-packaging. It will help also with conda-forge packaging.

• Closes #112

Add MANIFEST.in file

• this allows complete clarity and declarative specification of what to include or exclude in the packaging

:fire: NOTE: currently the following two files are missing from the .tar.gz aource on PyPI:

• LICENSE file

  The license file is necessary for conda-forge packaging as well.

• requirements.txt file

  The setup.py file looks for the requirements.txt file and since it's not present throws an error while trying to install from the downloaded .tar.gz source file.

:bulb: NO requirements.txt or py.typed FILE INCLUDED

Add py.typed file

This will enable support for type hinting in editors according to PEP-561.

The py.typed file is supposed to be an empty file placed inside the package folder auto_ts.

[sugatoray]

cc: @AutoViML

Question:

I see that you are excluding tests folder inside setup.py (line-16), however, I do not see there is any folder by that name under the root of the repository. Am I missing something? Or, did you mean to exlude auto_ts/test folder?

[AutoViML]

Ok done thanks @sugatoray 👍