Support http3

[ostcar]

Http3 uses udp instead of tcp. udp and tcp uses different ports. So the udp port 8000 has nothing to do with the tcp port 8000.

To use udp in docker, the udp port has also to be opened.

For example:

    ports:
      - 0.0.0.0:8000:8000
      - 0.0.0.0:8000:8000/udp

Currently, OpenSlides does not support http3. But I hope, with OpenSlides/OpenSlides#6553, http3 will be supported. Please change the creation of the docker-compose file, so it also opens the udp port

[ostcar]

See OpenSlides/OpenSlides#6558