Fix CI Docker pull failure by specifying etcd version tag

Co-authored-by: nomeguy <85475922+nomeguy@users.noreply.github.com>

Author: Copilot

.github/workflows/test.yml

@@ -16,7 +16,7 @@ jobs:
     runs-on: ubuntu-latest
     services:
       casbin:
-        image: quay.io/coreos/etcd
+        image: quay.io/coreos/etcd:v3.5.0
         ports:
           - 2379:2379
           - 2380:2380