Add CI workflow for JDK 17.

Author: liuzhaobo

.github/workflows/ci.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-20.04
     strategy:
       matrix:
-        java: [8, 11]
+        java: [8, 11, 17]
     steps:
       - name: Checkout
         uses: actions/checkout@v2