* build: use goreleaser to cross-compile binaries for all platforms and archs
The main motivation behind it is because "gox" is unmaintained and archived
and it does not support "linux/riscv64" as a target.
Right now, goreleaser is only building the binaries, and I've tried to replicate
the exact same way the old script does.
In the future, if so desired, goreleaser could be used to further automate the
build and release pipeline by creating the release in GitHub.
* build: create binaries and OCI image for linux/riscv64
