chore: update jdk to 21

Author: fankes

.github/workflows/docs-deploy.yml

@@ -27,10 +27,10 @@ jobs:
         uses: actions/setup-node@v4
         with:
           node-version: 18
-      - name: Prepare Java 17
+      - name: Prepare Java 21
         uses: actions/setup-java@v4
         with:
-          java-version: 17
+          java-version: 21
           java-package: jdk
           distribution: 'temurin'
           cache: 'gradle'