ci: avoid deprecated set-output command

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

.github/workflows/ci.yml

@@ -72,7 +72,7 @@ jobs:
       - name: Get Composer Cache Directory
         id: composer-cache
         run: |
-          echo "::set-output name=dir::$(composer config cache-files-dir)"
+          echo "dir=$(composer config cache-files-dir)" >> $GITHUB_OUTPUT
       - name: Cache composer dependencies
         uses: actions/cache@v4
         with: