Update gradle.yml

Author: Telesphoreo

.github/workflows/gradle.yml

@@ -7,12 +7,12 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v2
-      - name: Set up JDK 17
-        uses: actions/setup-java@v2
+      - uses: actions/checkout@v4
+      - name: Set up JDK 21
+        uses: actions/setup-java@v4
         with:
           distribution: temurin
-          java-version: 17
+          java-version: 21
           cache: gradle
       - name: Build with Gradle
         run: chmod a+x gradlew && ./gradlew build --no-daemon