use more modern Java

Author: StevenArzt

.github/workflows/ci.yml

@@ -53,10 +53,10 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@v2
-      - name: Use Java 8
+      - name: Use Java 11
         uses: actions/setup-java@v1
         with:
-          java-version: '8'
+          java-version: '11'
       - name: Deploy artifacts
         uses: samuelmeuli/action-maven-publish@v1
         with: