chore(ci): upgrade checkout action to v5

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: iktakahiro

.github/workflows/test.yaml

@@ -10,7 +10,7 @@ jobs:
       matrix:
         python-version: ["3.14"]
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - name: Set up uv
         uses: astral-sh/setup-uv@v6
         with: