Upgrade Java CI workflow to modern GitHub Actions setup.

Move to setup-java v4 with Temurin JDK 11 and Maven cache so CI matches current build requirements and avoids deprecated Node 20 action usage.

Made-with: Cursor

Author: gangz

.github/workflows/maven.yml

@@ -8,11 +8,13 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v1
-    - name: Set up JDK 1.8
-      uses: actions/setup-java@v1
+    - uses: actions/checkout@v4
+    - name: Set up JDK 11
+      uses: actions/setup-java@v4
       with:
-        java-version: 1.8
+        distribution: temurin
+        java-version: '11'
+        cache: maven
     - name: Install depended jars
       run: ./lib_install.sh
     - name: Build with Maven