Fix CI failure: specify etcd v3.5.0 Docker image tag

[Copilot]

CI fails because quay.io/coreos/etcd:latest no longer exists. The workflow was pulling the etcd container without an explicit version tag.

Changes

• Updated .github/workflows/test.yml to use quay.io/coreos/etcd:v3.5.0
• Version matches etcd client library in go.mod (v3.5.0)

services:
  casbin:
-   image: quay.io/coreos/etcd
+   image: quay.io/coreos/etcd:v3.5.0

Original prompt

---

This section details on the original issue you should resolve

<issue_title>[bug] fix CI error</issue_title>
<issue_description>see: https://github.com/casbin/etcd-watcher/actions/runs/20964431308/job/60250635133

feat: upgrade CI Go version to 1.23 casbin/etcd-watcher#37

[test (1.23)](https://github.com/casbin/etcd-watcher/actions/runs/20964431308/job/60250635133#logs)
failed 1 minute ago in 18s

Initialize containers

Checking docker version
Clean up resources from previous jobs
Create local container network
Starting casbin service container
  /usr/bin/docker pull quay.io/coreos/etcd
  Using default tag: latest
  Error response from daemon: manifest for quay.io/coreos/etcd:latest not found: manifest unknown: manifest unknown
  Warning: Docker pull failed with exit code 1, back off 8.22 seconds before retry.
  /usr/bin/docker pull quay.io/coreos/etcd
  Using default tag: latest
  Error response from daemon: manifest for quay.io/coreos/etcd:latest not found: manifest unknown: manifest unknown
  Warning: Docker pull failed with exit code 1, back off 2.91 seconds before retry.
  /usr/bin/docker pull quay.io/coreos/etcd
  Using default tag: latest
  Error response from daemon: manifest for quay.io/coreos/etcd:latest not found: manifest unknown: manifest unknown
  Error: Docker pull failed with exit code 1
```</issue_description>

## Comments on the Issue (you are @copilot in this section)

<comments>
</comments>

• Fixes [bug] fix CI error #30

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