Proxy test (#2172)

* Add proxy test on CI

* Add Brotli and Zstd dev packages to proxy test workflow

* Fix Docker Compose command for GitHub Actions compatibility

* Add proxy readiness check and netcat dependency

* Use netcat-openbsd instead of virtual netcat package

* Add proxy startup delay and debug logging

.gitignore

@@ -42,4 +42,4 @@ ipch
 *.pyc
 .*
 !/.gitattributes
-!/.travis.yml
+!/.github