revert to legacy set-output in test.yml

Author: ProjektGopher

.github/workflows/test.yml

@@ -27,7 +27,7 @@ jobs:
           coverage: none
       - name: Get composer cache directory
         id: composer-cache
-        run: echo "dir=$(composer config cache-files-dir)" >> $GITHUB_OUTPUT
+        run: echo "::set-output name=dir::$(composer config cache-files-dir)"
       - name: Setup composer cache
         uses: actions/cache@v4
         with: