Update actions/checkout to v6

Author: vietj

.github/workflows/ci.yml

@@ -17,7 +17,7 @@ jobs:
     runs-on: ${{ inputs.os }}
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           ref: ${{ inputs.branch }}
       - name: Install JDK

.github/workflows/deploy.yml

@@ -17,7 +17,7 @@ jobs:
       VERTX_NEXUS_PASSWORD: ${{ secrets.VERTX_NEXUS_PASSWORD }}
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           ref: ${{ inputs.branch }}
       - name: Install JDK