Update GH actions versions and ubuntu runner version

Author: atextor

.github/workflows/antora-build.yml

@@ -7,14 +7,14 @@ on:
 
 jobs:
   build-and-deploy:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
 
     steps:
     - name: Checkout
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
 
     - name: Set up JDK 17
-      uses: actions/setup-java@v3
+      uses: actions/setup-java@v4
       with:
         distribution: 'temurin'
         java-version: '17'