Replace pkg resources use

[loqs]

• setup.py: except ImportError for missing pkg_resources
  • Missing pkg_resources indicates setuptools 82 or newer which is more recent that than 18.5 so the version check using pkg_resources can safely be skipped.
  • This is an alternative to setup.py: handle missing pkg_resources import #592 that avoids using setuptools internal namespace setuptools._vendor.packaging.version.
• conftest.py: Replace pkg_resources use with packaging
  • This is python 3+ only and intended to be merged after Only support python versions that receive security updates #580
  • I can refactor it so it supports 2.7+ if desired.