[actions] Replace jdk 16 with 17 and 18-ea

Author: hazendaz

.github/workflows/ci.yaml

@@ -8,7 +8,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macOS-latest, windows-latest]
-        java: [8, 11, 16]
+        java: [8, 11, 17, 18-ea]
       fail-fast: false
       max-parallel: 4
     name: Test JDK ${{ matrix.java }}, ${{ matrix.os }}