update go releaser

[franklinlindemberg]

When trying to release grpcui, I got the following error

# golang.org/x/tools/internal/tokeninternal
../../go/pkg/mod/golang.org/x/tools@v0.13.0/internal/tokeninternal/tokeninternal.go:78:9: invalid array length -delta * delta (constant -256 of type int64)
make: *** [release] Error 1

Updating gorelease seems to fix the issue

---

Note

Low Risk
Only release tooling and config change; no application runtime or security-sensitive logic is modified.

Overview
Upgrades the release pipeline from GoReleaser v1.21.0 to v2.5.0 so make release works again (the PR author hit a build failure in golang.org/x/tools when using the older toolchain).

The Makefile now installs github.com/goreleaser/goreleaser/v2@v2.5.0. .goreleaser.yml is aligned with GoReleaser v2: adds version: 2 and replaces archive format / format_overrides.format with the v2 formats list syntax (still tar.gz by default, zip on Windows).

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