Fix including JSON tables in distributed library: Use package_data over include_package_data

Building the source or binary distributions of this python library produces a package without any of the table files present. include_package_data=True is insufficient and seemed to not pick up the files.

Indeed, this StackOverflow entry seems to detail the woe: https://stackoverflow.com/questions/7522250/how-to-include-package-data-with-setuptools-distutils

By using package_data not only does it now seem to work on both source and binary distributions (ie the files get copied when running python setup.py sdist bdist) but there's also finer-grained control on what files to include in the final package/library.

This is relevant/important as I, and others, may rely upon using pip3 install git+https://github.com/wmo-im/GTStoWIS2.git#main instead of cloning the repo locally and installing from that directory as indicated in your README.rst instructions.

Bug Report Approach 1

Steps to reproduce

pip3 install git+https://github.com/wmo-im/GTStoWIS2.git#main
python3

import GTStoWIS2
topic_mapper = GTStoWIS2.GTStoWIS2()

Expected

It works, with an instance of the class

Actual

>>> GTStoWIS2.GTStoWIS2()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/justin/.pyenv/versions/3.9.5/lib/python3.9/site-packages/GTStoWIS2/__init__.py", line 97, in __init__
    self._readTables()
  File "/Users/justin/.pyenv/versions/3.9.5/lib/python3.9/site-packages/GTStoWIS2/__init__.py", line 42, in _readTables
    with open( f, 'r',encoding="UTF-8" ) as m:
FileNotFoundError: [Errno 2] No such file or directory: '/Users/justin/.pyenv/versions/3.9.5/lib/python3.9/site-packages/GTStoWIS2/TableA.json'

Bug Report Approach 2

Steps to reproduce

git clone https://github.com/wmo-im/GTStoWIS2.git
cd GTStoWIS2
python3 setup.py sdist bdist
cd dist
tar xvfz GTStoWIS2-0.0.2.tar.gz
ls GTStoWIS2-0.0.2/GTStoWIS2

Observe the resulting list of files from inside the package/library.

Expected

The __init__.py file along with its siblings Table*.json files

Actual

Just the __init__.py file alone.

wmo-im / GTStoWIS2