Upgrade actions/checkout from v2 to v5

Author: beacoder

.github/workflows/test.yml

@@ -29,6 +29,6 @@ jobs:
       with:
         version: ${{ matrix.emacs_version }}
 
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v5
     - name: Run tests
       run: make compile