fix php8 refresh workflow

requires updating the commit action due to
https://github.com/github-actions-x/commit/issues/30

.github/workflows/refresh-php8.yml

@@ -13,7 +13,7 @@ jobs:
 
     steps:
       - name: Checkout php8 branch
-        uses: actions/checkout@v2
+        uses: actions/checkout@v2.9
         with:
           # directly checkout the php8 branch
           ref: php8