fix GitHub Workflow to check syntax with Vale

Not using latest version, and pin to a specific version.

Author: fharper

.github/workflows/check-syntax.yml

@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout this repository
-        uses: actions/checkout@main
+        uses: actions/checkout@v4.1.4
 
       - name: Download .vale.ini
         run: wget https://raw.githubusercontent.com/fharper/gh-configs/main/.vale.ini -O .vale.ini