RFR: Update GHA to jdk20 [v7]

Mon Dec 12 16:29:50 UTC 2022

On Mon, 12 Dec 2022 16:21:35 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

>> This PR updates the github actions on the jdk20 branch
>
> Maurizio Cimadamore has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Add comment

Marked as reviewed by jvernee (no project role).

-------------

PR: https://git.openjdk.org/jextract/pull/96