Replace deprecated set-output in GHA

Author: Namoshek

.github/workflows/tests.yml

@@ -41,7 +41,7 @@ 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@v3