Avoid deprecated set-output command [docs-only]

.github/workflows/ci_test.yml

@@ -36,7 +36,7 @@ jobs:
           message=$(git log -1 --pretty=format:'%B')
           re="\[(docs.only|skip-tests).*\]"
           if [[ $message =~ $re ]]; then
-            echo "::set-output name=match::true"
+            echo "match=true" >> $GITHUB_OUTPUT
             echo "$message -> Match is true"
           else
             echo "$message -> Match is false"