slapos_web_deploy: log_parse callback supports newer version of ansible

1) when ansible is still python2 and the callback "json" was introduced
(e.g. in Ubuntu 18.04) we need to use "strict_import" to be sure to use
the json python module and not the json callback

2) when ansible is python3 the syntax must be python3 compatible

3) also remove an uneeded data.copy()