Update workflow

.github/workflows/build.yml

@@ -10,23 +10,26 @@ jobs:
   build:
     strategy:
       matrix:
-        java: [ "17" ] # Latest version
-
+        java: [
+          "17", # Old LTS
+          "21" # Current LTS
+          ]
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4.1.1
-      - uses: gradle/wrapper-validation-action@v1.1.0
+      - uses: actions/checkout@v4
+      - uses: gradle/wrapper-validation-action@v3
       - name: Setup Java JDK
-        uses: actions/setup-java@v4.0.0
+        uses: actions/setup-java@v4
         with:
           distribution: "temurin"
           java-version: ${{ matrix.java }}
       - name: Grant execute permission
         run: chmod +x ./gradlew
       - name: Build with Gradle
         run: ./gradlew build
-      - name: Upload a Build Artifact
-        uses: actions/[email protected]
+      - if: matrix.java == '17'
+        name: Upload a Build Artifact
+        uses: actions/upload-artifact@v4
         with: 
           name: modid
           path: build/libs/*.jar