chore(ci): Update the JDK version in the desktop build workflow

Author: Jankin-Wu

.github/workflows/build-desktop.yml

@@ -218,10 +218,10 @@ jobs:
       - name: Checkout code
         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'
 
       - name: Setup Gradle