investigate http-compatibility-tests

[pjfanning]

• https://github.com/apache/incubator-pekko-http/tree/main/http-compatibility-tests
• don't seem to be wired into our sbt setup
• In fix more akka naming #354 - one of the files in http-compatibility-tests seems to refer to a class that has been renamed long ago (Akka to Pekko) so the code shouldn't have been able to compile