[CI] Add JDK 21-ea to the build matrix.

Author: vyazelenko

.github/workflows/ci.yml

@@ -28,7 +28,7 @@ jobs:
  strategy:
  fail-fast: false
  matrix:
- java: [ '8', '11', '17', '20' ]
+ java: [ '8', '11', '17', '21-ea' ]
  os: [ 'ubuntu-22.04', 'windows-latest' ]
  steps:
  - name: Checkout code