chore(ci): refresh GitHub Actions to current majors in test and release workflows

[pbesret]

Problem

The GitHub Actions used by test.yml and release.yml are several majors behind upstream (checkout v3, setup-go v4, setup-terraform v2, import-gpg v5, goreleaser-action v4.4.0). Six Dependabot PRs from 2023-2024 (#108, #109, #110, #111, #121, #129) went stale: two were obsolete (#108 targets a deleted workflow; #129 bumps terraform-plugin-sdk/v2 to 2.32.0 while main is on 2.35.0) and the four action bumps target versions that are themselves outdated. Dependabot auto-paused due to prolonged inactivity on those PRs.

Scope

• Triage the six stale Dependabot PRs (done: Bump leonsteinhaeuser/project-beta-automations from 2.1.0 to 2.2.1 #108 and Bump github.com/hashicorp/terraform-plugin-sdk/v2 from 2.27.0 to 2.32.0 #129 closed as obsolete; Bump goreleaser/goreleaser-action from 4.4.0 to 5.0.0 #109/Bump crazy-max/ghaction-import-gpg from 5 to 6 #110/Bump actions/checkout from 3 to 4 #111/Bump actions/setup-go from 4 to 5 #121 closed as superseded).
• Refresh all workflow actions to the current upstream majors in a single reviewed PR (chore(ci): refresh GitHub Actions to current majors in test and release workflows #492): checkout v7, setup-go v7, setup-terraform v4, import-gpg v7, goreleaser-action v7, with the GoReleaser distribution pinned to ~> v2 instead of latest.

Risk

CI-only change: no provider code, not user-facing (no CHANGELOG entry). test.yml changes are fully exercised by the PR's own CI (green). release.yml is only exercised at the next v* tag push; a failure there would occur before any publication and is recoverable by re-running after a fix. The per-usage breaking-change audit and the independent adversarial review (Codex: GO, no blocking or minor findings) are recorded in PR #492.