fix(ci): harden GitHub Actions workflows against expression injection (#10200)

.github/workflows/sdk-security.yml

@@ -25,6 +25,8 @@ jobs:
     steps:
       - name: Checkout repository
         uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        with:
+          persist-credentials: false
 
       - name: Check for SDK changes
         id: check-changes