RFR: GHA: Resolve deprecation warnings

[altrisi]

This PR resolves deprecation warnings in the GHA workflow by updating dependencies and replacing the deprecated `set-output` with `GITHUB_OUTPUT`.

v2 to v3 major in `checkout` just updated the node version.

Github Script v3->v6 also needed a small code change (`github.repos`->`github.rest.repos`), following the documentation.

GHA workflows still pass with these changes.

Note that I don't have a JBS account to be able to make an issue for this PR.

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Commit messages:
 - Update GHScript to v6
 - Skara GHA: Resolve deprecation warnings

Changes: https://git.openjdk.org/skara/pull/1552/files
 Webrev: https://webrevs.openjdk.org/?repo=skara&pr=1552&range=00
  Stats: 12 lines in 1 file changed: 0 ins; 0 del; 12 mod
  Patch: https://git.openjdk.org/skara/pull/1552.diff
  Fetch: git fetch https://git.openjdk.org/skara.git pull/1552/head:pull/1552

PR: https://git.openjdk.org/skara/pull/1552