Fix + Docker image

[micw]

Hello, I cherry-picked the fix from d9k and added a Dockerfile + GH action.

[jakob]

Can you explain what this is good for?

[micw]

It compiles and creates a docker image for the proxy by using github action automation Edit: and the cherry-picked fix allows to compile under a recent linux.

[jakob]

Yes, that is obvious from the changes. Can youplease explain what you would use this for? How would you even use the docker image?

[micw]

Sure. I'm using it for a testcase where I simulate a bad internet connection. I use testcontainers.org to run the stuff I need for my integration tests, so I built the container. I created the PR because I tought it could be useful for anyone else.