CI: set checkout to version 4

Author: gynt

.github/workflows/msbuild.yml

@@ -18,7 +18,7 @@ jobs:
     #   matrix:
     #     BUILD_CONFIGURATION: [Debug, Release]
     steps:
-    - uses: actions/checkout@latest
+    - uses: actions/checkout@v4
 
     - name: Add MSBuild to PATH
       uses: microsoft/setup-msbuild@v1