Remove unnecessary comment.

Capturing the ImportError is a common idiom in Ansible modules, and it
is not specific to tox.

roles/openshift_health_checker/library/aos_version.py

@@ -24,7 +24,7 @@ IMPORT_EXCEPTION = None
 try:
     import yum  # pylint: disable=import-error
 except ImportError as err:
-    IMPORT_EXCEPTION = err  # in tox test env, yum import fails
+    IMPORT_EXCEPTION = err
 
 
 class AosVersionException(Exception):