fix(ci): pin + cache

.github/workflows/test.yml

@@ -25,6 +25,8 @@ jobs:
     steps:
       - name: Check out the codebase
         uses: actions/checkout@2541b1294d2704b0964813337f33b291d3f8596b # 3.0.2
+        with:
+          ref: ${{ github.event.pull_request.head.sha }}
 
       - name: Configure VirtualBox
         run: |-