feat: add GHCR support and security improvements

[maateen]

This PR introduces several significant improvements to the project's CI pipeline, security, and licensing.

Changes

• fix(ci): Fixed matrix value alignment in merge job
• feat(ci): Added support for GitHub Container Registry (GHCR)
  • Images now publish to both Docker Hub and GHCR
  • Updated authentication and push configurations
• feat: Enhanced Dockerfile security and build process
• chore: Changed license from GPLv3 to MIT
  • Updated LICENSE file
  • Updated license references in Dockerfile
  • Maintained consistency with upstream Beanstalkd project
• Updated README with:
  • New registry information
  • MIT license badge
  • Better usage examples