ci: 升级 actions 到 v5（消除弃用警告）

setup-java 升 v4→v5（官方警告点名）；checkout、upload-artifact 一并升 v5（已核实 tag 存在）。消除 Node.js 20 弃用与 setup-java v4 弃用警告。

.github/workflows/build.yml

@@ -12,10 +12,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
 
       - name: Set up JDK 25
-        uses: actions/setup-java@v4
+        uses: actions/setup-java@v5
         with:
           distribution: 'temurin'
           java-version: '25'
@@ -27,7 +27,7 @@ jobs:
         run: ./gradlew build --stacktrace
 
       - name: Upload build artifacts
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v5
         with:
           name: mod-jar
           path: build/libs/*.jar

.github/workflows/release.yml

@@ -19,10 +19,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
 
       - name: Set up JDK 25
-        uses: actions/setup-java@v4
+        uses: actions/setup-java@v5
         with:
           distribution: 'temurin'
           java-version: '25'