Updated the rack-sdk-version to 2.4.0 and modified the build matrix and image used in the GitHub Actions workflow.

Added a debugging step to display container environment details and check for premake5 installation.

Added a step to install premake for Windows and Linux builds using various package managers or by downloading the binary.

Removed installation step for premake5 from build workflow.

Added step to install premake5 for Windows/Linux builds.

Updated the Docker image for the build job and disabled the macOS build job.

This workflow builds a VCV Rack plugin for multiple platforms and publishes it if a tag is created. It includes steps for modifying the plugin version, building for Windows, Linux, and macOS, and uploading artifacts.