Update actions/checkout action to v5

Author: renovate[bot]

.github/workflows/main.yml

@@ -6,7 +6,7 @@ jobs:
 
     steps:
       - name: Begin CI...
-        uses: actions/checkout@v2
+        uses: actions/checkout@v5
 
       - name: Use Node 12
         uses: actions/setup-node@v2