[actions] Java 16 is GA, add 17-ea

Author: harawata

.github/workflows/ci.yaml

@@ -24,7 +24,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macOS-latest, windows-latest]
-        java: [8, 11, 15, 16-ea]
+        java: [8, 11, 15, 16, 17-ea]
       fail-fast: false
       max-parallel: 4
     name: Test JDK ${{ matrix.java }}, ${{ matrix.os }}