Bump actions/checkout from 2 to 4 (#1276)

.github/workflows/deploy-docs.yml

@@ -17,7 +17,7 @@ jobs:
     # if: github.repository_owner == 'spring-projects'
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           ref: docs-build
           fetch-depth: 1

.github/workflows/maven.yml

@@ -15,7 +15,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - name: Set up JDK
         uses: actions/setup-java@v3
         with: