test: use latest v6 tag

Author: Greg Bowler

.github/workflows/ci-show-output-log.yml

@@ -10,7 +10,7 @@ jobs:
       - uses: actions/checkout@v3
 
       - name: Install dependencies
-        uses: php-actions/composer@master
+        uses: php-actions/composer@v6
         with:
           php_version: 8.1
           ssh_key: ${{ secrets.SSH_KEY }}

.github/workflows/ci.yaml

@@ -10,7 +10,7 @@ jobs:
       - uses: actions/checkout@v3
 
       - name: Install dependencies
-        uses: php-actions/composer@master
+        uses: php-actions/composer@v6
 
         with:
           php_version: '8.1'