ci: Update actions/checkout

Author: aklinker1

.github/workflows/validate.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-20.04
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - uses: oven-sh/setup-bun@v2