Update Github workflow to checkout V4

.github/workflows/test.yml

@@ -40,7 +40,7 @@ jobs:
       run: curl -fsSL https://raw.github.com/doublep/eldev/master/webinstall/github-eldev | sh
 
     - name: Check out the source code
-      uses: actions/checkout@v2
+      uses: actions/checkout@v4
 
     - name: Install Elisp dependencies
       run: eldev prepare test