build: remove deprecated set-output command (#19)

Author: vintagesucks

.github/workflows/build.yml

@@ -35,7 +35,7 @@ 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 dependencies
         uses: actions/cache@v4