Update CI to use Java 11 as base build for Vert.x 5

Author: vietj

.github/workflows/ci-5.x.yml

@@ -14,9 +14,9 @@ jobs:
       matrix:
         include:
           - os: ubuntu-latest
-            jdk: 8
+            jdk: 11
           - os: windows-latest
-            jdk: 8
+            jdk: 11
           - os: ubuntu-latest
             jdk: 17
     uses: ./.github/workflows/ci.yml
@@ -31,5 +31,5 @@ jobs:
     uses: ./.github/workflows/deploy.yml
     with:
       branch: ${{ github.event.pull_request.head.sha || github.ref_name }}
-      jdk: 8
+      jdk: 11
     secrets: inherit