chore(deps): update actions/checkout action to v4 (#496)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

.github/workflows/ci.yml

@@ -25,7 +25,7 @@ jobs:
         run: sudo apt-get update || exit 0
 
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Setup node
         uses: actions/setup-node@v4
@@ -66,7 +66,7 @@ jobs:
         run: sudo apt-get install -y graphicsmagick
 
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Setup node
         uses: actions/setup-node@v4
@@ -125,7 +125,7 @@ jobs:
 
         # Checkouts
       - name: Checkout (rest)
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Setup node
         uses: actions/setup-node@v4
@@ -144,7 +144,7 @@ jobs:
 
       # Prepare API
       - name: Checkout (api)
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           repository: opencollective/opencollective-api
           path: opencollective-api