ci: caching, java v2

Author: TobiTenno

.github/workflows/ci.yaml

@@ -13,9 +13,10 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v2
       - name: Setup JDK 16
-        uses: actions/setup-java@v1
+        uses: actions/setup-java@v2
         with:
           java-version: 16
+          distribution: 'temurin'
           cache: 'maven'
       - name: Install packages
         run: |