jdk 21 test

Author: xuwei-k

.github/workflows/ci.yml

@@ -13,7 +13,7 @@ jobs:
       matrix:
         include:
           - java: 8
-          - java: 17
+          - java: 21
     steps:
     - uses: actions/checkout@v4
     - uses: actions/setup-java@7a6d8a8234af8eb26422e24e3006232cccaa061b # v4.6.0