Add and expose at runtime in a standard format the __version__ attribute

[filipecosta90]

We should be able expose the package version at runtime via __version__ attribute while ensuring a single source of truth for version number.

Here's a discussion on how to standardize this info: https://stackoverflow.com/questions/458550/standard-way-to-embed-version-into-python-package

Example of redistimeseries-py:

attribute
https://github.com/RedisTimeSeries/redistimeseries-py/blob/master/redistimeseries/_version.py

setup.py way of reading it:
https://github.com/RedisTimeSeries/redistimeseries-py/blob/master/setup.py#L8