Fix deprecation warning

[Honny1]

This PR fixes:
DeprecationWarning: pkg_resources is deprecated as an API. See https://setuptools.pypa.io/en/latest/pkg_resources.html

Reproducer with tox:

diff --git a/tox.ini b/tox.ini
index 8d55872..5431db5 100644
--- a/tox.ini
+++ b/tox.ini
@@ -17,6 +17,7 @@ commands =
         py.test --cov=openscap_report --cov-append --cov-report=term-missing -m "not integration_test"
         py.test --cov-report=term-missing -m "not unit_test"
 deps =
+    setuptools>=67.6.1
     pytest
     pytest-cov
     jsonschema

Fixes: #203