Update actions/checkout action to v4

Author: renovate[bot]

.github/workflows/deploy.yml

@@ -15,7 +15,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout your repository using git
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Install, build, and upload your site output
         uses: withastro/action@v0

.github/workflows/test.yml

@@ -10,7 +10,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Install Node.js
         uses: actions/setup-node@v3