Describe the bug
I am running popeye with docker and I noticed that the same command using image v0.11.3 and v0.20.0 put the report file in different locations:
/tmp/popeye/report_file.html for v0.11.3
and
/tmp/popeye/<cluster_name or user>/<cluster_name or user>/my_report.txt for v0.20.0 and after (including v.0.21.3).

Setting a POPEYE_REPORT_DIR only replaces /tmp/popeye with the path from env variable.

To Reproduce
Steps to reproduce the behavior:

1. Run docker command with both versions:

docker run --rm -v $(pwd)/config:/home/nonroot/.kube/config -v /tmp:/tmp \
  derailed/popeye:v0.21.3  -n bar --save --output-file my_report.txt
--result--
/tmp/popeye/<cluster_name or user>/<cluster_name or user>/my_report.txt

docker run --rm -v $(pwd)/config:/home/nonroot/.kube/config -v /tmp:/tmp \
  derailed/popeye:v0.11.3  -n bar --save --output-file my_report.txt
--result--
/tmp/popeye/my_report.txt

Expected behavior
Is there a way to have a fixed path that I can set with POPEYE_REPORT_DIR and nothing extra to be added?