Update actions/checkout action to v4

Author: renovate[bot]

.github/workflows/caddy.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0
 

.github/workflows/pr-test.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Install Compose
         uses: ndeloof/[email protected]

.github/workflows/uptime-kuma.yml

@@ -16,7 +16,7 @@ jobs:
       url: https://status.aosus.org
     steps:
       - name: checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0