Add JDK 21 support (#310)

vharseko

23.38.2023 cb69ead94eadce90fd0616b5af263603feee78ba

 .github/workflows/build.yml

@@ -10,7 +10,7 @@
    runs-on: ${{ matrix.os }}
    strategy:
      matrix:
        java: [ '8','11','17','19']
        java: [ '8','11','17','21']
        os: [ 'ubuntu-latest', 'macos-latest', 'windows-latest' ]
      fail-fast: false
    steps: