update jdk version

Author: zhlee1997

.github/workflows/build-docker.yaml

@@ -22,10 +22,10 @@ jobs:
     steps:
       - name: Checkout Repository
         uses: actions/checkout@v4
-      - name: Set up JDK 17
+      - name: Set up JDK 21
         uses: actions/setup-java@v4
         with:
-          java-version: "17"
+          java-version: "21"
           distribution: "temurin"
           cache: maven
       - name: Build insta-service-registry with Maven