Add Linux ppc64le (IBM Power) build target and modernise deprecated GoReleaser flags

[ALutz273]

Summary

vip-manager currently ships only linux/{386,amd64,arm64} and windows/{386,amd64} artefacts. There is no linux/ppc64le build, so PostgreSQL-on-IBM-Power users (Patroni + etcd + vip-manager on RHEL/SLES ppc64le) have to compile from source. Additionally, the GoReleaser invocation in Makefile and README.md still uses the deprecated --skip-publish and --rm-dist flags.

Proposed changes

1. .goreleaser.yml — extend the build matrix:

goarch:
  - amd64
  - "386"
  - arm64
  - ppc64le
goppc64:
  - power9   # covers POWER9 / POWER10 / POWER11
ignore:
  - { goos: windows, goarch: ppc64le }
  - { goos: windows, goarch: arm64 }

Note: Go's GOPPC64 accepts power8 / power9 / power10 only — there is no power11 target yet. POWER11 hardware runs power10 binaries unchanged.

2. Makefile + README.md — replace deprecated flags:

- goreleaser release --snapshot --skip-publish --rm-dist
+ goreleaser release --snapshot --skip=publish --clean

Offer

Happy to submit a PR and validate the resulting .rpm / .deb on RHEL 9 ppc64le (POWER10) against a Patroni + etcd v3 cluster.

[pashagolub]

Oh, cool! Yes, please, submit a PR! We'd be happy to review and accept! Thanks

[df7cb]

If you are looking for .deb, apt.postgresql.org has been shipping vip-manager2/ppc64el packages for years already. It's also included in Debian/Ubuntu main.

[markwort]

I just raised an issue to try to get the ppc64le version published via postgresql.org YUM repositories:
pgdg-packaging/pgdg-rpms#184