Update test workflow

Author: APickledWalrus

.github/workflows/gradle.yml

@@ -11,25 +11,27 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repo
-        uses: actions/checkout@v2
-      - name: Set up JDK 11
-        uses: actions/setup-java@v1
+        uses: actions/checkout@v5
+      - name: Set up JDK 21
+        uses: actions/setup-java@v5
         with:
-          java-version: 17
+          java-version: 21
+          distribution: 'adopt'
+          cache: gradle
       - name: Grant execute permission for gradlew
         run: chmod +x gradlew
       - name: Build with Gradle
         run: ./gradlew build
       - name: Upload artifacts
-        uses: actions/upload-artifact@master
+        uses: actions/upload-artifact@v4
         with:
           path: build/libs/*.jar
   test:
     runs-on: ubuntu-latest
     needs: [build]
     steps:
       - name: Checkout repo
-        uses: actions/checkout@v2
+        uses: actions/checkout@v5
       - name: Download artifacts
         uses: actions/download-artifact@v4
         with: