ci: 更新 release workflow actions 版本，消除弃用警告

- actions/checkout v3 → v4
- actions/setup-java v3 → v4
- gradle-build-action v2 → gradle/actions/setup-gradle v4
- JDK 8 → JDK 21 (项目已需要 JDK 21 编译)

Author: Z User

.github/workflows/release.yml

@@ -9,16 +9,16 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - name: Setup JDK
-        uses: actions/setup-java@v3
+        uses: actions/setup-java@v4
         with:
-          java-version: 8
+          java-version: 21
           distribution: zulu
 
       - name: Build
-        uses: gradle/gradle-build-action@v2.4.0
+        uses: gradle/actions/setup-gradle@v4
         with:
           arguments: shadowJar