Update workflow

.github/workflows/gradle.yml

@@ -6,16 +6,18 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
     - name: Set up JDK 1.8
-      uses: actions/setup-java@v2
+      uses: actions/setup-java@v4
       with:
         distribution: 'adopt'
         java-version: '8'
+    - name: Gradle Wrapper Validation
+      uses: gradle/actions/wrapper-validation@v3
     - name: Build with Gradle
       run: ./gradlew nightlyBuild
     - name: Upload Nightly Build
-      uses: actions/upload-artifact@v2
+      uses: actions/upload-artifact@v4
       if: success()
       with:
         name: skript-placeholders-nightly