update action

Author: hidakatsuya

.github/workflows/test.yml

@@ -22,7 +22,7 @@ jobs:
     steps:
       - run: sudo apt-get install at-spi2-core
 
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - uses: hidakatsuya/action-setup-diff-pdf@v1
         with: