RFR: 8295714: GHA ::set-output is deprecated and will be removed

[Magnus Ihse Bursie]

On Thu, 20 Oct 2022 10:00:14 GMT, Magnus Ihse Bursie <ihse at openjdk.org> wrote:

> We need to transition to use the new `$GITHUB_OUTPUT` method instead. 
> 
> This needs to be fixed since it is currently spamming the summary with warnings, and will stop working soon.

My fixes were green, but all of the annoying log spam was not gone. After some digging, it turned out that GitHub's own `download-artifact at v3` was not clean, so I've upgraded it to `download-artifact at v3.0.1` which was released just hours (!) ago. (Luckily I did not try to research this yesterday...)

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PR: https://git.openjdk.org/jdk/pull/10785