CI: Replace the deprecated `::set-output` command by writing to $GITHUB_OUTPUT in workflow definition

See "CI: Replace the deprecated `::set-output` command by writing to
$GITHUB_OUTPUT in matrix.py" for the reasoning behind this commit.

(cherry picked from commit b87ecbb179b897521aa217a3341ba5529b36f447)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 0855bad3117bd027795303d717e39cebc6ebadaa)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 824ed8f40926f1ee2624a5988708202367c6c126)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
3 files changed