Add GoReleaser

[brushmate]

This pull request adds GoReleaser for creating new releases of the oidc-token-ferry. This makes it easy to create releases for e.g. M1 Macs which are currently not available. What do you think about this?

[twz123]

Thanks @brushmate!

I'm a bit on the fence about goreleaser. Basically, it's its own mini-build system for Go. A Makefile somehow doesn't make much sense then, unless as a simple shell snippet runner, à la npx run and friends. Personally, I have never seen a real advantage for goreleaser. Cross compilation is easy enough to realise in pure Go via GOOS and GOARCH. I think oidc-token-ferry could do without release-tarballs with license and readme and so on. The automatic creation of GitHub releases can be done with special GitHub actions. Especially in the release process, goreleaser has the disadvantage that it can't be easily split into several parallel GitHub jobs. But with the compilation times of oidc-token-ferry I think this is negligible :-) The upx packing of the binaries is probably not possible to do with goreleaser as well. The cosign/SBOM support would be IMO maybe the only interesting thing.

That said, since you already did the work, let's go all in goreleaser :D

One thing I'd like to be changed here: Have a push/PR GitHub Actions workflow as there has been before, but use something like goreleaser build --snapshot --single-target instead of make. Maybe it makes sense to add another matrix entry for darwin/GOARCH=arm64, too.

I still have some other nits, but I can do that in a later PR and add you as a reviewer if you're okay with that.