[BUG] unstable unit test when run by github action

[mga-chka]

Describe the bug
for an unkown reason the test following test TestServe/http_gzipped_POST_request randomly fails when it's run on a github action and never when it's run on a laptop.

This tests makes the build sometimes unstable & therefore unreliable.

For example, here are recent examples of build failures because of this test
https://github.com/ContentSquare/chproxy/actions/runs/4385351732/jobs/7677964078
https://github.com/ContentSquare/chproxy/actions/runs/4864160906/jobs/8672815035
https://github.com/ContentSquare/chproxy/actions/runs/4871170693/jobs/8687808711

The issue is always the same tests and the root cause is always
main_test.go:1165: unexpected error: Post "http://127.0.0.1:9090": EOF