Bug fixes and improvements

[gaby]

• Updated docker-compose file
• Refactor Dockerfile
• Updated llama.cpp tag to master-02d6988
• Added support for cleaning untagged images (current over +500)
• Only push PR images if code owners matches @nsarrazin or @gaby (there has a to be a better way of doing this...)
• Support for building arm64 and amd64 concurrently (it still slow...)

[gaby]

These changes can be tested using:

docker run -d \
     -v weights:/usr/src/app/weights -v datadb:/data/db/ \
     -p 8008:8008 ghcr.io/nsarrazin/serge:pr-202