Fix CI checkout

Author: lsegal

.github/workflows/ci.yml

@@ -48,7 +48,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v6
+        uses: actions/checkout@v1
       - name: Install Ruby & 'bundle install'
         if: matrix.container == null
         uses: ruby/setup-ruby@v1