Stop using the deprecated set-output command

The `set-output` command is deprecated and will be disabled soon. Please upgrade to using Environment Files. For more information see: https://github.blog/changelog/2022-10-11-github-actions-deprecating-save-state-and-set-output-commands/

.github/workflows/ci.yaml

@@ -31,7 +31,7 @@ jobs:
 
       - name: Get composer cache directory
         id: composer-cache
-        run: echo "::set-output name=dir::$(composer config cache-files-dir)"
+        run: echo "dir=$(composer config cache-files-dir)" >> $GITHUB_OUTPUT
 
       - name: "Cache composer"
         uses: actions/cache@v3