upgrade actions/checkout version

Author: dhacks541

.github/workflows/test_code.yml

@@ -10,7 +10,7 @@ jobs:
   build:
     runs-on: windows-latest
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
     - name: Cache pip
       uses: actions/cache@v4
       with: