CI: migrate away from deprecated "set-output" syntax

As noted in [1] and the warnings the CI itself is spewing echoing
outputs to stdout is deprecated, and they should be written to
"$GITHUB_OUTPUT" instead.

1. https://github.blog/changelog/2022-10-11-github-actions-deprecating-save-state-and-set-output-commands/

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: avar

.github/workflows/l10n.yml

@@ -23,8 +23,8 @@ jobs:
             base=${{ github.event.before }}
             head=${{ github.event.after }}
           fi
-          echo "::set-output name=base::$base"
-          echo "::set-output name=head::$head"
+          echo base=$base >>$GITHUB_OUTPUT
+          echo head=$head >>$GITHUB_OUTPUT
       - name: Run partial clone
         run: |
           git -c init.defaultBranch=master init --bare .

.github/workflows/main.yml

@@ -34,7 +34,7 @@ jobs:
           then
             enabled=no
           fi
-          echo "::set-output name=enabled::$enabled"
+          echo "enabled=$enabled" >>$GITHUB_OUTPUT
       - name: skip if the commit or tree was already tested
         id: skip-if-redundant
         uses: actions/github-script@v3