update build.yml

.github/workflows/build.yml

@@ -8,13 +8,17 @@ on:
 
 jobs:
   build:
-
     runs-on: ubuntu-latest
 
     steps:
       - name: Checkout repository
         uses: actions/checkout@v2
 
+      - name: Set up JDK 17
+        uses: actions/setup-java@v2
+        with:
+          java-version: '17'
+
       - name: Build JAR
         run: |
           chmod +x ./gradlew