Remove use of packaging module to avoid installation errors

[borzunov]

Currently, setup.py uses packaging module to parse Golang versions. This leads to errors in case of installing hivemind to a clean Python installation, since packaging is not a part of setuptools and is not installed by default.

#269 attempted to fix that, however this fix has no effect since the packaging module is imported in the beginning of setup.py before requirements.txt is even parsed.

The problem can be easily reproduced by creating a new virtualenv environment and trying to install hivemind inside it with pip install -e .[dev].

This PR solves the problem by removing the usage of the packaging module completely.

[codecov]

Codecov Report

Merging #284 (180db82) into master (ef2c6ab) will increase coverage by 0.08%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #284      +/-   ##
==========================================
+ Coverage   72.25%   72.34%   +0.08%     
==========================================
  Files          62       62              
  Lines        5594     5594              
==========================================
+ Hits         4042     4047       +5     
+ Misses       1552     1547       -5     

Impacted Files	Coverage Δ
hivemind/dht/node.py	93.23% <0.00%> (+1.25%)	⬆️